| Message ID | 20210113174623.1397914-1-tfoucu@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel] libavformat/matroskaenc.c: Add option to set timecodescale | expand |
| Context | Check | Description |
|---|---|---|
| andriy/x86_make | success | Make finished |
| andriy/x86_make_fate | success | Make fate finished |
| andriy/PPC64_make | success | Make finished |
| andriy/PPC64_make_fate | success | Make fate finished |
Jan 13, 2021, 18:46 by tfoucu@gmail.com: > By default the time code scale in a MKV file in millisecond. With this > option we can set the time code scale to microsecond or nanoseconds for > very high frame rate. > --- > libavformat/matroskaenc.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c > index 233c472b8f..cfad6a4693 100644 > --- a/libavformat/matroskaenc.c > +++ b/libavformat/matroskaenc.c > @@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext { > int default_mode; > > uint32_t segment_uid[4]; > + > + int64_t timecodescale; > } MatroskaMuxContext; > > /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint, > @@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s) > return ret; > pb = mkv->info.bc; > > - put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000); > + put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale); > if ((tag = av_dict_get(s->metadata, "title", NULL, 0))) > put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value); > if (!(s->flags & AVFMT_FLAG_BITEXACT)) { > @@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s) > // after 4k and on a keyframe > if (IS_SEEKABLE(pb, mkv)) { > if (mkv->cluster_time_limit < 0) > - mkv->cluster_time_limit = 5000; > + mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale); > if (mkv->cluster_size_limit < 0) > mkv->cluster_size_limit = 5 * 1024 * 1024; > } else { > if (mkv->cluster_time_limit < 0) > - mkv->cluster_time_limit = 1000; > + mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale); > if (mkv->cluster_size_limit < 0) > mkv->cluster_size_limit = 32 * 1024; > } > @@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s) > } > > // ms precision is the de-facto standard timescale for mkv files > - avpriv_set_pts_info(st, 64, 1, 1000); > + avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale); > > if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) { > if (mkv->mode == MODE_WEBM) { > @@ -2795,6 +2797,7 @@ static const AVOption options[] = { > { "infer", "For each track type, mark the first track of disposition default as default; if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, "default_mode" }, > { "infer_no_subs", "For each track type, mark the first track of disposition default as default; for audio and video: if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" }, > { "passthrough", "Use the disposition flag as-is", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, "default_mode" }, > + { "timecodescale", "Time code scale for all tracks in nanoseconds", OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, 1000000000, FLAGS }, > { NULL }, > }; > This, x10000000000000000! Can we make it 1ns by default? Or maybe autodetect the highest precision timebase of all streams and use it? Let's not keep generating garbage files with shitty rounding that players have to work around to recover the original timestamp based on framerate to reduce jitter (mpv does this!). Also WebM mode should disable this, because the spec is dumb and specifies a 1ms precision for no good reason.
HI Lynne On Wed, Jan 13, 2021 at 10:30 AM Lynne <dev@lynne.ee> wrote: > Jan 13, 2021, 18:46 by tfoucu@gmail.com: > > > By default the time code scale in a MKV file in millisecond. With this > > option we can set the time code scale to microsecond or nanoseconds for > > very high frame rate. > > --- > > libavformat/matroskaenc.c | 11 +++++++---- > > 1 file changed, 7 insertions(+), 4 deletions(-) > > > > diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c > > index 233c472b8f..cfad6a4693 100644 > > --- a/libavformat/matroskaenc.c > > +++ b/libavformat/matroskaenc.c > > @@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext { > > int default_mode; > > > > uint32_t segment_uid[4]; > > + > > + int64_t timecodescale; > > } MatroskaMuxContext; > > > > /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint, > > @@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s) > > return ret; > > pb = mkv->info.bc; > > > > - put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000); > > + put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale); > > if ((tag = av_dict_get(s->metadata, "title", NULL, 0))) > > put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value); > > if (!(s->flags & AVFMT_FLAG_BITEXACT)) { > > @@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s) > > // after 4k and on a keyframe > > if (IS_SEEKABLE(pb, mkv)) { > > if (mkv->cluster_time_limit < 0) > > - mkv->cluster_time_limit = 5000; > > + mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale); > > if (mkv->cluster_size_limit < 0) > > mkv->cluster_size_limit = 5 * 1024 * 1024; > > } else { > > if (mkv->cluster_time_limit < 0) > > - mkv->cluster_time_limit = 1000; > > + mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale); > > if (mkv->cluster_size_limit < 0) > > mkv->cluster_size_limit = 32 * 1024; > > } > > @@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s) > > } > > > > // ms precision is the de-facto standard timescale for mkv files > > - avpriv_set_pts_info(st, 64, 1, 1000); > > + avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale); > > > > if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) { > > if (mkv->mode == MODE_WEBM) { > > @@ -2795,6 +2797,7 @@ static const AVOption options[] = { > > { "infer", "For each track type, mark the first track of disposition > default as default; if none exists, mark the first track as default.", 0, > AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, > "default_mode" }, > > { "infer_no_subs", "For each track type, mark the first track of > disposition default as default; for audio and video: if none exists, mark > the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = > DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" }, > > { "passthrough", "Use the disposition flag as-is", 0, > AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, > "default_mode" }, > > + { "timecodescale", "Time code scale for all tracks in nanoseconds", > OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, > 1000000000, FLAGS }, > > { NULL }, > > }; > > > > This, x10000000000000000! > Can we make it 1ns by default? Or maybe autodetect the highest precision > timebase of all streams and use it? > The MKV spec seems to indicate a default value of ms. I did not want to change it in this patch. > Let's not keep generating garbage files with shitty rounding that players > have to work around to recover the original timestamp based on framerate > to reduce jitter (mpv does this!). > +1 on this, but I'm worry, we could break a lot of decoder which may not follow the correct timecodescale (Which we found out in our system a while back) > Also WebM mode should disable this, because the spec is dumb and specifies > a 1ms precision for no good reason. > If we keep the default value of ms, then this will not change any webm unless a user decides to generate a Webm file and set this flag. Do you want me to log an error saying that using this flag to set something other than ms for webm is incorrect? > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
On 1/13/2021 2:46 PM, Thierry Foucu wrote: > By default the time code scale in a MKV file in millisecond. With this > option we can set the time code scale to microsecond or nanoseconds for > very high frame rate. > --- > libavformat/matroskaenc.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c > index 233c472b8f..cfad6a4693 100644 > --- a/libavformat/matroskaenc.c > +++ b/libavformat/matroskaenc.c > @@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext { > int default_mode; > > uint32_t segment_uid[4]; > + > + int64_t timecodescale; > } MatroskaMuxContext; > > /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint, > @@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s) > return ret; > pb = mkv->info.bc; > > - put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000); > + put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale); > if ((tag = av_dict_get(s->metadata, "title", NULL, 0))) > put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value); > if (!(s->flags & AVFMT_FLAG_BITEXACT)) { > @@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s) > // after 4k and on a keyframe > if (IS_SEEKABLE(pb, mkv)) { > if (mkv->cluster_time_limit < 0) > - mkv->cluster_time_limit = 5000; > + mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale); Either 1000000000LL, or use av_rescale(). Same for the two below > if (mkv->cluster_size_limit < 0) > mkv->cluster_size_limit = 5 * 1024 * 1024; > } else { > if (mkv->cluster_time_limit < 0) > - mkv->cluster_time_limit = 1000; > + mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale); > if (mkv->cluster_size_limit < 0) > mkv->cluster_size_limit = 32 * 1024; > } > @@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s) > } > > // ms precision is the de-facto standard timescale for mkv files > - avpriv_set_pts_info(st, 64, 1, 1000); > + avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale); > > if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) { > if (mkv->mode == MODE_WEBM) { > @@ -2795,6 +2797,7 @@ static const AVOption options[] = { > { "infer", "For each track type, mark the first track of disposition default as default; if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, "default_mode" }, > { "infer_no_subs", "For each track type, mark the first track of disposition default as default; for audio and video: if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" }, > { "passthrough", "Use the disposition flag as-is", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, "default_mode" }, > + { "timecodescale", "Time code scale for all tracks in nanoseconds", OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, 1000000000, FLAGS }, > { NULL }, > }; Does this cover all cases? A timecodescale of 1000000 was implied until now, so many parts of the code could be hardcoding it in a non obvious way. I see for example MATROSKA_ID_DURATION is set as av_rescale(s->duration, 1000, AV_TIME_BASE). Should that AV_TIME_BASE be changed to mkv->timecodescale? The spec says "Duration of the Segment in nanoseconds based on TimestampScale."
a note with this change: If we set the timecodescale to microsecond, and we encode a 30 fps video, the duration of each frame are then 33333 us. In this case, (int16_t)cluster_time != cluster_time Will almost every time faile and we will need to create a new block per frame (it seems to me at least) Because in the block header, there is a timestamp relative to Cluster timestamp (signed int16) which cannot represent 33333 On Wed, Jan 13, 2021 at 12:02 PM James Almer <jamrial@gmail.com> wrote: > On 1/13/2021 2:46 PM, Thierry Foucu wrote: > > By default the time code scale in a MKV file in millisecond. With this > > option we can set the time code scale to microsecond or nanoseconds for > > very high frame rate. > > --- > > libavformat/matroskaenc.c | 11 +++++++---- > > 1 file changed, 7 insertions(+), 4 deletions(-) > > > > diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c > > index 233c472b8f..cfad6a4693 100644 > > --- a/libavformat/matroskaenc.c > > +++ b/libavformat/matroskaenc.c > > @@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext { > > int default_mode; > > > > uint32_t segment_uid[4]; > > + > > + int64_t timecodescale; > > } MatroskaMuxContext; > > > > /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint, > > @@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s) > > return ret; > > pb = mkv->info.bc; > > > > - put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000); > > + put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale); > > if ((tag = av_dict_get(s->metadata, "title", NULL, 0))) > > put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value); > > if (!(s->flags & AVFMT_FLAG_BITEXACT)) { > > @@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s) > > // after 4k and on a keyframe > > if (IS_SEEKABLE(pb, mkv)) { > > if (mkv->cluster_time_limit < 0) > > - mkv->cluster_time_limit = 5000; > > + mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale); > > Either 1000000000LL, or use av_rescale(). Same for the two below > > > if (mkv->cluster_size_limit < 0) > > mkv->cluster_size_limit = 5 * 1024 * 1024; > > } else { > > if (mkv->cluster_time_limit < 0) > > - mkv->cluster_time_limit = 1000; > > + mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale); > > if (mkv->cluster_size_limit < 0) > > mkv->cluster_size_limit = 32 * 1024; > > } > > @@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s) > > } > > > > // ms precision is the de-facto standard timescale for mkv > files > > - avpriv_set_pts_info(st, 64, 1, 1000); > > + avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale); > > > > if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) { > > if (mkv->mode == MODE_WEBM) { > > @@ -2795,6 +2797,7 @@ static const AVOption options[] = { > > { "infer", "For each track type, mark the first track of > disposition default as default; if none exists, mark the first track as > default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, > FLAGS, "default_mode" }, > > { "infer_no_subs", "For each track type, mark the first track of > disposition default as default; for audio and video: if none exists, mark > the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = > DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" }, > > { "passthrough", "Use the disposition flag as-is", 0, > AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, > "default_mode" }, > > + { "timecodescale", "Time code scale for all tracks in nanoseconds", > OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, > 1000000000, FLAGS }, > > { NULL }, > > }; > > Does this cover all cases? A timecodescale of 1000000 was implied until > now, so many parts of the code could be hardcoding it in a non obvious way. > > I see for example MATROSKA_ID_DURATION is set as av_rescale(s->duration, > 1000, AV_TIME_BASE). Should that AV_TIME_BASE be changed to > mkv->timecodescale? The spec says "Duration of the Segment in > nanoseconds based on TimestampScale." > Interesting. I did not have to change this because if I check the Metadata DURATION coming from the demuxer with a default ms and set to microsecond, I do see in both: DURATION : 00:00:01.001000000 or is it another duration I need to look at, like this one: https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/matroskaenc.c#L1863 See output: # default behavoir ./ffmpeg -f lavfi -i "testsrc=r=30000/1001" -debug_ts -t 1 -y -f matroska /tmp/test.mkv ./ffmpeg -i /tmp/test.mkv ffmpeg version N-100413-g3799e77f93 Copyright (c) 2000-2020 the FFmpeg developers built with gcc 10 (Debian 10.2.0-19) configuration: --disable-optimizations libavutil 56. 62.100 / 56. 62.100 libavcodec 58.115.102 / 58.115.102 libavformat 58. 65.100 / 58. 65.100 libavdevice 58. 11.103 / 58. 11.103 libavfilter 7. 93.100 / 7. 93.100 libswscale 5. 8.100 / 5. 8.100 libswresample 3. 8.100 / 3. 8.100 Input #0, matroska,webm, from '/tmp/test.mkv': Metadata: ENCODER : Lavf58.65.100 Duration: 00:00:01.00, start: 0.000000, bitrate: 412 kb/s Stream #0:0: Video: mpeg4 (Simple Profile), yuv420p(tv, progressive), 320x240 [SAR 1:1 DAR 4:3], 29.97 fps, 29.97 tbr, 1k tbn, 30k tbc (default) Metadata: ENCODER : Lavc58.115.102 mpeg4 DURATION : 00:00:01.001000000 # set the timecodescale to microsecond ./ffmpeg -f lavfi -i "testsrc=r=30000/1001" -debug_ts -t 1 -timecodescale 1000 -y -f matroska /tmp/test_2.mkv ./ffmpeg -i /tmp/test_2.mkv ffmpeg version N-100413-g3799e77f93 Copyright (c) 2000-2020 the FFmpeg developers built with gcc 10 (Debian 10.2.0-19) configuration: --disable-optimizations libavutil 56. 62.100 / 56. 62.100 libavcodec 58.115.102 / 58.115.102 libavformat 58. 65.100 / 58. 65.100 libavdevice 58. 11.103 / 58. 11.103 libavfilter 7. 93.100 / 7. 93.100 libswscale 5. 8.100 / 5. 8.100 libswresample 3. 8.100 / 3. 8.100 Input #0, matroska,webm, from '/tmp/test_2.mkv': Metadata: ENCODER : Lavf58.65.100 Duration: 00:00:01.00, start: 0.000000, bitrate: 416 kb/s Stream #0:0: Video: mpeg4 (Simple Profile), yuv420p(tv, progressive), 320x240 [SAR 1:1 DAR 4:3], 29.97 fps, 29.97 tbr, 1000k tbn, 30k tbc (default) Metadata: ENCODER : Lavc58.115.102 mpeg4 DURATION : 00:00:01.001000000
On 1/13/2021 5:50 PM, Thierry Foucu wrote: > a note with this change: > If we set the timecodescale to microsecond, and we encode a 30 fps video, > the duration of each frame are then 33333 us. > In this case, > (int16_t)cluster_time != cluster_time > Will almost every time faile and we will need to create a new block per > frame (it seems to me at least) > Because in the block header, there is a timestamp relative to Cluster > timestamp (signed int16) which cannot represent 33333 > > On Wed, Jan 13, 2021 at 12:02 PM James Almer <jamrial@gmail.com> wrote: > >> On 1/13/2021 2:46 PM, Thierry Foucu wrote: >>> By default the time code scale in a MKV file in millisecond. With this >>> option we can set the time code scale to microsecond or nanoseconds for >>> very high frame rate. >>> --- >>> libavformat/matroskaenc.c | 11 +++++++---- >>> 1 file changed, 7 insertions(+), 4 deletions(-) >>> >>> diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c >>> index 233c472b8f..cfad6a4693 100644 >>> --- a/libavformat/matroskaenc.c >>> +++ b/libavformat/matroskaenc.c >>> @@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext { >>> int default_mode; >>> >>> uint32_t segment_uid[4]; >>> + >>> + int64_t timecodescale; >>> } MatroskaMuxContext; >>> >>> /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint, >>> @@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s) >>> return ret; >>> pb = mkv->info.bc; >>> >>> - put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000); >>> + put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale); >>> if ((tag = av_dict_get(s->metadata, "title", NULL, 0))) >>> put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value); >>> if (!(s->flags & AVFMT_FLAG_BITEXACT)) { >>> @@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s) >>> // after 4k and on a keyframe >>> if (IS_SEEKABLE(pb, mkv)) { >>> if (mkv->cluster_time_limit < 0) >>> - mkv->cluster_time_limit = 5000; >>> + mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale); >> >> Either 1000000000LL, or use av_rescale(). Same for the two below >> >>> if (mkv->cluster_size_limit < 0) >>> mkv->cluster_size_limit = 5 * 1024 * 1024; >>> } else { >>> if (mkv->cluster_time_limit < 0) >>> - mkv->cluster_time_limit = 1000; >>> + mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale); >>> if (mkv->cluster_size_limit < 0) >>> mkv->cluster_size_limit = 32 * 1024; >>> } >>> @@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s) >>> } >>> >>> // ms precision is the de-facto standard timescale for mkv >> files >>> - avpriv_set_pts_info(st, 64, 1, 1000); >>> + avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale); >>> >>> if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) { >>> if (mkv->mode == MODE_WEBM) { >>> @@ -2795,6 +2797,7 @@ static const AVOption options[] = { >>> { "infer", "For each track type, mark the first track of >> disposition default as default; if none exists, mark the first track as >> default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, >> FLAGS, "default_mode" }, >>> { "infer_no_subs", "For each track type, mark the first track of >> disposition default as default; for audio and video: if none exists, mark >> the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = >> DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" }, >>> { "passthrough", "Use the disposition flag as-is", 0, >> AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, >> "default_mode" }, >>> + { "timecodescale", "Time code scale for all tracks in nanoseconds", >> OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, >> 1000000000, FLAGS }, >>> { NULL }, >>> }; >> >> Does this cover all cases? A timecodescale of 1000000 was implied until >> now, so many parts of the code could be hardcoding it in a non obvious way. >> >> I see for example MATROSKA_ID_DURATION is set as av_rescale(s->duration, >> 1000, AV_TIME_BASE). Should that AV_TIME_BASE be changed to >> mkv->timecodescale? The spec says "Duration of the Segment in >> nanoseconds based on TimestampScale." >> > > Interesting. I did not have to change this because if I check the Metadata > DURATION coming from the demuxer with a default ms and set to microsecond, > I do see in both: > DURATION : 00:00:01.001000000 > > or is it another duration I need to look at, like this one: > https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/matroskaenc.c#L1863 That and the one immediately after it are the ones i was talking about, yes. In any case, it seems to be a temporary value written to the output that will afterwards be overwritten in https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/matroskaenc.c#L2559 when writing the trailer. The commit that added the code in mkv_write_header() is 70c1647a350. I guess you could ensure the temp value written there is correct by forcing the muxing process to stop without calling mkv_write_trailer(), or commenting out the code writing the final duration value. > > See output: > # default behavoir > ./ffmpeg -f lavfi -i "testsrc=r=30000/1001" -debug_ts -t 1 -y -f matroska > /tmp/test.mkv > ./ffmpeg -i /tmp/test.mkv > ffmpeg version N-100413-g3799e77f93 Copyright (c) 2000-2020 the FFmpeg > developers > built with gcc 10 (Debian 10.2.0-19) > configuration: --disable-optimizations > libavutil 56. 62.100 / 56. 62.100 > libavcodec 58.115.102 / 58.115.102 > libavformat 58. 65.100 / 58. 65.100 > libavdevice 58. 11.103 / 58. 11.103 > libavfilter 7. 93.100 / 7. 93.100 > libswscale 5. 8.100 / 5. 8.100 > libswresample 3. 8.100 / 3. 8.100 > Input #0, matroska,webm, from '/tmp/test.mkv': > Metadata: > ENCODER : Lavf58.65.100 > Duration: 00:00:01.00, start: 0.000000, bitrate: 412 kb/s > Stream #0:0: Video: mpeg4 (Simple Profile), yuv420p(tv, progressive), > 320x240 [SAR 1:1 DAR 4:3], 29.97 fps, 29.97 tbr, 1k tbn, 30k tbc (default) > Metadata: > ENCODER : Lavc58.115.102 mpeg4 > DURATION : 00:00:01.001000000 > > # set the timecodescale to microsecond > ./ffmpeg -f lavfi -i "testsrc=r=30000/1001" -debug_ts -t 1 -timecodescale > 1000 -y -f matroska /tmp/test_2.mkv > ./ffmpeg -i /tmp/test_2.mkv > ffmpeg version N-100413-g3799e77f93 Copyright (c) 2000-2020 the FFmpeg > developers > built with gcc 10 (Debian 10.2.0-19) > configuration: --disable-optimizations > libavutil 56. 62.100 / 56. 62.100 > libavcodec 58.115.102 / 58.115.102 > libavformat 58. 65.100 / 58. 65.100 > libavdevice 58. 11.103 / 58. 11.103 > libavfilter 7. 93.100 / 7. 93.100 > libswscale 5. 8.100 / 5. 8.100 > libswresample 3. 8.100 / 3. 8.100 > Input #0, matroska,webm, from '/tmp/test_2.mkv': > Metadata: > ENCODER : Lavf58.65.100 > Duration: 00:00:01.00, start: 0.000000, bitrate: 416 kb/s > Stream #0:0: Video: mpeg4 (Simple Profile), yuv420p(tv, progressive), > 320x240 [SAR 1:1 DAR 4:3], 29.97 fps, 29.97 tbr, 1000k tbn, 30k tbc > (default) > Metadata: > ENCODER : Lavc58.115.102 mpeg4 > DURATION : 00:00:01.001000000 > > > _______________________________________________ >> ffmpeg-devel mailing list >> ffmpeg-devel@ffmpeg.org >> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel >> >> To unsubscribe, visit link above, or email >> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". > > >
Jan 13, 2021, 20:58 by tfoucu@gmail.com: > HI Lynne > > On Wed, Jan 13, 2021 at 10:30 AM Lynne <> dev@lynne.ee> > wrote: > >> Jan 13, 2021, 18:46 by >> tfoucu@gmail.com>> : >> >> > By default the time code scale in a MKV file in millisecond. With this >> > option we can set the time code scale to microsecond or nanoseconds for >> > very high frame rate. >> > --- >> > libavformat/matroskaenc.c | 11 +++++++---- >> > 1 file changed, 7 insertions(+), 4 deletions(-) >> > >> > diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c >> > index 233c472b8f..cfad6a4693 100644 >> > --- a/libavformat/matroskaenc.c >> > +++ b/libavformat/matroskaenc.c >> > @@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext { >> > int default_mode; >> > >> > uint32_t segment_uid[4]; >> > + >> > + int64_t timecodescale; >> > } MatroskaMuxContext; >> > >> > /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint, >> > @@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s) >> > return ret; >> > pb = mkv->info.bc; >> > >> > - put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000); >> > + put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale); >> > if ((tag = av_dict_get(s->metadata, "title", NULL, 0))) >> > put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value); >> > if (!(s->flags & AVFMT_FLAG_BITEXACT)) { >> > @@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s) >> > // after 4k and on a keyframe >> > if (IS_SEEKABLE(pb, mkv)) { >> > if (mkv->cluster_time_limit < 0) >> > - mkv->cluster_time_limit = 5000; >> > + mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale); >> > if (mkv->cluster_size_limit < 0) >> > mkv->cluster_size_limit = 5 * 1024 * 1024; >> > } else { >> > if (mkv->cluster_time_limit < 0) >> > - mkv->cluster_time_limit = 1000; >> > + mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale); >> > if (mkv->cluster_size_limit < 0) >> > mkv->cluster_size_limit = 32 * 1024; >> > } >> > @@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s) >> > } >> > >> > // ms precision is the de-facto standard timescale for mkv files >> > - avpriv_set_pts_info(st, 64, 1, 1000); >> > + avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale); >> > >> > if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) { >> > if (mkv->mode == MODE_WEBM) { >> > @@ -2795,6 +2797,7 @@ static const AVOption options[] = { >> > { "infer", "For each track type, mark the first track of disposition >> default as default; if none exists, mark the first track as default.", 0, >> AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, >> "default_mode" }, >> > { "infer_no_subs", "For each track type, mark the first track of >> disposition default as default; for audio and video: if none exists, mark >> the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = >> DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" }, >> > { "passthrough", "Use the disposition flag as-is", 0, >> AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, >> "default_mode" }, >> > + { "timecodescale", "Time code scale for all tracks in nanoseconds", >> OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, >> 1000000000, FLAGS }, >> > { NULL }, >> > }; >> > >> >> This, x10000000000000000! >> Can we make it 1ns by default? Or maybe autodetect the highest precision >> timebase of all streams and use it? >> > > The MKV spec seems to indicate a default value of ms. I did not want to > change it in this patch. > The spec was written in 2001ish. Mobile phones didn't even exist back then, I think, and internet video must have been 12fps mpeg2. 1ms didn't make much sense back then, and it makes exactly no sense at at all right now with phones regularly shooting at hundreds of frames per second. >> Let's not keep generating garbage files with shitty rounding that players >> have to work around to recover the original timestamp based on framerate >> to reduce jitter (mpv does this!). >> > > +1 on this, but I'm worry, we could break a lot of decoder which may not > follow the correct timecodescale (Which we found out in our system a while > back) > I think that's a bug in their code, and we should help them fix it by changing the default. It's kind of important, as nothing will change unless we start to generate files with better precision by default. For decades the main complaint about Matroska has been the ridiculously low timestamp precision most files have. Even the spec authors agree. There were talks to add hacks to correct the precision of the timestamps in a compatible way with buggy demuxers some years ago, but nothing came of it. I'd really like to not have to tell users "please enable this magical demuxer option to not mess up high framerate files or induce jitter". I'd be so much better to say "oh, your files don't play correctly? You can enable this magic option and remux the file, and also report this to the authors so they can fix it. The former is reversible and preserves timestamp precision. The latter is irreversible without guesses.
On 1/13/2021 4:58 PM, Thierry Foucu wrote: > HI Lynne > > On Wed, Jan 13, 2021 at 10:30 AM Lynne <dev@lynne.ee> wrote: > >> Jan 13, 2021, 18:46 by tfoucu@gmail.com: >> >>> By default the time code scale in a MKV file in millisecond. With this >>> option we can set the time code scale to microsecond or nanoseconds for >>> very high frame rate. >>> --- >>> libavformat/matroskaenc.c | 11 +++++++---- >>> 1 file changed, 7 insertions(+), 4 deletions(-) >>> >>> diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c >>> index 233c472b8f..cfad6a4693 100644 >>> --- a/libavformat/matroskaenc.c >>> +++ b/libavformat/matroskaenc.c >>> @@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext { >>> int default_mode; >>> >>> uint32_t segment_uid[4]; >>> + >>> + int64_t timecodescale; >>> } MatroskaMuxContext; >>> >>> /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint, >>> @@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s) >>> return ret; >>> pb = mkv->info.bc; >>> >>> - put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000); >>> + put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale); >>> if ((tag = av_dict_get(s->metadata, "title", NULL, 0))) >>> put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value); >>> if (!(s->flags & AVFMT_FLAG_BITEXACT)) { >>> @@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s) >>> // after 4k and on a keyframe >>> if (IS_SEEKABLE(pb, mkv)) { >>> if (mkv->cluster_time_limit < 0) >>> - mkv->cluster_time_limit = 5000; >>> + mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale); >>> if (mkv->cluster_size_limit < 0) >>> mkv->cluster_size_limit = 5 * 1024 * 1024; >>> } else { >>> if (mkv->cluster_time_limit < 0) >>> - mkv->cluster_time_limit = 1000; >>> + mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale); >>> if (mkv->cluster_size_limit < 0) >>> mkv->cluster_size_limit = 32 * 1024; >>> } >>> @@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s) >>> } >>> >>> // ms precision is the de-facto standard timescale for mkv files >>> - avpriv_set_pts_info(st, 64, 1, 1000); >>> + avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale); >>> >>> if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) { >>> if (mkv->mode == MODE_WEBM) { >>> @@ -2795,6 +2797,7 @@ static const AVOption options[] = { >>> { "infer", "For each track type, mark the first track of disposition >> default as default; if none exists, mark the first track as default.", 0, >> AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, >> "default_mode" }, >>> { "infer_no_subs", "For each track type, mark the first track of >> disposition default as default; for audio and video: if none exists, mark >> the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = >> DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" }, >>> { "passthrough", "Use the disposition flag as-is", 0, >> AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, >> "default_mode" }, >>> + { "timecodescale", "Time code scale for all tracks in nanoseconds", >> OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, >> 1000000000, FLAGS }, >>> { NULL }, >>> }; >>> >> >> This, x10000000000000000! >> Can we make it 1ns by default? Or maybe autodetect the highest precision >> timebase of all streams and use it? >> > > The MKV spec seems to indicate a default value of ms. I did not want to > change it in this patch. > > >> Let's not keep generating garbage files with shitty rounding that players >> have to work around to recover the original timestamp based on framerate >> to reduce jitter (mpv does this!). >> > > +1 on this, but I'm worry, we could break a lot of decoder which may not > follow the correct timecodescale (Which we found out in our system a while > back) > > >> Also WebM mode should disable this, because the spec is dumb and specifies >> a 1ms precision for no good reason. >> > > If we keep the default value of ms, then this will not change any webm > unless a user decides to generate a Webm file and set this flag. > Do you want me to log an error saying that using this flag to set something > other than ms for webm is incorrect? The webm spec states "The TimecodeScale element SHOULD be set to a default of 1.000.000 nanoseconds.", so it's not forbidden per se. Does libwebm handle files with a different TimecodeScale than the default? If so, then it's fine. Otherwise, I agree we should probably error out. > > >> _______________________________________________ >> ffmpeg-devel mailing list >> ffmpeg-devel@ffmpeg.org >> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel >> >> To unsubscribe, visit link above, or email >> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". > > >
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c index 233c472b8f..cfad6a4693 100644 --- a/libavformat/matroskaenc.c +++ b/libavformat/matroskaenc.c @@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext { int default_mode; uint32_t segment_uid[4]; + + int64_t timecodescale; } MatroskaMuxContext; /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint, @@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s) return ret; pb = mkv->info.bc; - put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000); + put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale); if ((tag = av_dict_get(s->metadata, "title", NULL, 0))) put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value); if (!(s->flags & AVFMT_FLAG_BITEXACT)) { @@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s) // after 4k and on a keyframe if (IS_SEEKABLE(pb, mkv)) { if (mkv->cluster_time_limit < 0) - mkv->cluster_time_limit = 5000; + mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale); if (mkv->cluster_size_limit < 0) mkv->cluster_size_limit = 5 * 1024 * 1024; } else { if (mkv->cluster_time_limit < 0) - mkv->cluster_time_limit = 1000; + mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale); if (mkv->cluster_size_limit < 0) mkv->cluster_size_limit = 32 * 1024; } @@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s) } // ms precision is the de-facto standard timescale for mkv files - avpriv_set_pts_info(st, 64, 1, 1000); + avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale); if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) { if (mkv->mode == MODE_WEBM) { @@ -2795,6 +2797,7 @@ static const AVOption options[] = { { "infer", "For each track type, mark the first track of disposition default as default; if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, "default_mode" }, { "infer_no_subs", "For each track type, mark the first track of disposition default as default; for audio and video: if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" }, { "passthrough", "Use the disposition flag as-is", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, "default_mode" }, + { "timecodescale", "Time code scale for all tracks in nanoseconds", OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, 1000000000, FLAGS }, { NULL }, };