| Message ID | 20230303210815.23692-1-dheitmueller@ltnglobal.com |
|---|---|
| State | Accepted |
| Commit | 8fd345f0180c655d18071d0445d797f27bb1efe7 |
| Headers | show |
| Series | [FFmpeg-devel,v2,1/3] decklink: Don't take for granted that first frame to decklink output will be PTS 0 | expand |
| Context | Check | Description |
|---|---|---|
| yinshiyou/make_loongarch64 | success | Make finished |
| yinshiyou/make_fate_loongarch64 | success | Make fate finished |
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
On Fri, 3 Mar 2023, Devin Heitmueller wrote: > The existing code assumed that the first frame received by the decklink > output would always be PTS zero. However if running in other timing > modes than the default of CBR, items such as frame dropping at the > beginning may result in starting at a non-zero PTS. > > For example, in our setup because we discard probing data and run > with "-vsync 2" the first video frame scheduled to the decklink > output will have a PTS around 170. Scheduling frames too far into > the future will either fail or cause a backlog of frames scheduled > far enough into the future that the entire pipeline will stall. > > Issue can be reproduced with the following command-line: > > ./ffmpeg -copyts -i foo.ts -f decklink -vcodec v210 -ac 2 'DeckLink Duo (4)' > > Keep track of the PTS of the first frame received, so that when > we enable start playback we can provide that value to the decklink > driver. > > Thanks to Marton Balint for review and suggestion to use > AV_NOPTS_VALUE rather than zero for the initial value. > > Signed-off-by: Devin Heitmueller <dheitmueller@ltnglobal.com> > --- > libavdevice/decklink_common.h | 1 + > libavdevice/decklink_enc.cpp | 8 ++++++-- > 2 files changed, 7 insertions(+), 2 deletions(-) Thanks, will apply the series. Regards, Marton > > diff --git a/libavdevice/decklink_common.h b/libavdevice/decklink_common.h > index 79d6ac5b38..088e165ee7 100644 > --- a/libavdevice/decklink_common.h > +++ b/libavdevice/decklink_common.h > @@ -118,6 +118,7 @@ struct decklink_ctx { > > /* Status */ > int playback_started; > + int64_t first_pts; > int64_t last_pts; > unsigned long frameCount; > unsigned int dropped; > diff --git a/libavdevice/decklink_enc.cpp b/libavdevice/decklink_enc.cpp > index fb686b9032..5a435ddc78 100644 > --- a/libavdevice/decklink_enc.cpp > +++ b/libavdevice/decklink_enc.cpp > @@ -486,6 +486,9 @@ static int decklink_write_video_packet(AVFormatContext *avctx, AVPacket *pkt) > ctx->frames_buffer_available_spots--; > pthread_mutex_unlock(&ctx->mutex); > > + if (ctx->first_pts == AV_NOPTS_VALUE) > + ctx->first_pts = pkt->pts; > + > /* Schedule frame for playback. */ > hr = ctx->dlo->ScheduleVideoFrame((class IDeckLinkVideoFrame *) frame, > pkt->pts * ctx->bmd_tb_num, > @@ -505,14 +508,14 @@ static int decklink_write_video_packet(AVFormatContext *avctx, AVPacket *pkt) > " Video may misbehave!\n"); > > /* Preroll video frames. */ > - if (!ctx->playback_started && pkt->pts > ctx->frames_preroll) { > + if (!ctx->playback_started && pkt->pts > (ctx->first_pts + ctx->frames_preroll)) { > av_log(avctx, AV_LOG_DEBUG, "Ending audio preroll.\n"); > if (ctx->audio && ctx->dlo->EndAudioPreroll() != S_OK) { > av_log(avctx, AV_LOG_ERROR, "Could not end audio preroll!\n"); > return AVERROR(EIO); > } > av_log(avctx, AV_LOG_DEBUG, "Starting scheduled playback.\n"); > - if (ctx->dlo->StartScheduledPlayback(0, ctx->bmd_tb_den, 1.0) != S_OK) { > + if (ctx->dlo->StartScheduledPlayback(ctx->first_pts * ctx->bmd_tb_num, ctx->bmd_tb_den, 1.0) != S_OK) { > av_log(avctx, AV_LOG_ERROR, "Could not start scheduled playback!\n"); > return AVERROR(EIO); > } > @@ -559,6 +562,7 @@ av_cold int ff_decklink_write_header(AVFormatContext *avctx) > ctx->list_formats = cctx->list_formats; > ctx->preroll = cctx->preroll; > ctx->duplex_mode = cctx->duplex_mode; > + ctx->first_pts = AV_NOPTS_VALUE; > if (cctx->link > 0 && (unsigned int)cctx->link < FF_ARRAY_ELEMS(decklink_link_conf_map)) > ctx->link = decklink_link_conf_map[cctx->link]; > cctx->ctx = ctx; > -- > 2.35.1.655.ga68dfadae5 > > _______________________________________________ > 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/libavdevice/decklink_common.h b/libavdevice/decklink_common.h index 79d6ac5b38..088e165ee7 100644 --- a/libavdevice/decklink_common.h +++ b/libavdevice/decklink_common.h @@ -118,6 +118,7 @@ struct decklink_ctx { /* Status */ int playback_started; + int64_t first_pts; int64_t last_pts; unsigned long frameCount; unsigned int dropped; diff --git a/libavdevice/decklink_enc.cpp b/libavdevice/decklink_enc.cpp index fb686b9032..5a435ddc78 100644 --- a/libavdevice/decklink_enc.cpp +++ b/libavdevice/decklink_enc.cpp @@ -486,6 +486,9 @@ static int decklink_write_video_packet(AVFormatContext *avctx, AVPacket *pkt) ctx->frames_buffer_available_spots--; pthread_mutex_unlock(&ctx->mutex); + if (ctx->first_pts == AV_NOPTS_VALUE) + ctx->first_pts = pkt->pts; + /* Schedule frame for playback. */ hr = ctx->dlo->ScheduleVideoFrame((class IDeckLinkVideoFrame *) frame, pkt->pts * ctx->bmd_tb_num, @@ -505,14 +508,14 @@ static int decklink_write_video_packet(AVFormatContext *avctx, AVPacket *pkt) " Video may misbehave!\n"); /* Preroll video frames. */ - if (!ctx->playback_started && pkt->pts > ctx->frames_preroll) { + if (!ctx->playback_started && pkt->pts > (ctx->first_pts + ctx->frames_preroll)) { av_log(avctx, AV_LOG_DEBUG, "Ending audio preroll.\n"); if (ctx->audio && ctx->dlo->EndAudioPreroll() != S_OK) { av_log(avctx, AV_LOG_ERROR, "Could not end audio preroll!\n"); return AVERROR(EIO); } av_log(avctx, AV_LOG_DEBUG, "Starting scheduled playback.\n"); - if (ctx->dlo->StartScheduledPlayback(0, ctx->bmd_tb_den, 1.0) != S_OK) { + if (ctx->dlo->StartScheduledPlayback(ctx->first_pts * ctx->bmd_tb_num, ctx->bmd_tb_den, 1.0) != S_OK) { av_log(avctx, AV_LOG_ERROR, "Could not start scheduled playback!\n"); return AVERROR(EIO); } @@ -559,6 +562,7 @@ av_cold int ff_decklink_write_header(AVFormatContext *avctx) ctx->list_formats = cctx->list_formats; ctx->preroll = cctx->preroll; ctx->duplex_mode = cctx->duplex_mode; + ctx->first_pts = AV_NOPTS_VALUE; if (cctx->link > 0 && (unsigned int)cctx->link < FF_ARRAY_ELEMS(decklink_link_conf_map)) ctx->link = decklink_link_conf_map[cctx->link]; cctx->ctx = ctx;
The existing code assumed that the first frame received by the decklink output would always be PTS zero. However if running in other timing modes than the default of CBR, items such as frame dropping at the beginning may result in starting at a non-zero PTS. For example, in our setup because we discard probing data and run with "-vsync 2" the first video frame scheduled to the decklink output will have a PTS around 170. Scheduling frames too far into the future will either fail or cause a backlog of frames scheduled far enough into the future that the entire pipeline will stall. Issue can be reproduced with the following command-line: ./ffmpeg -copyts -i foo.ts -f decklink -vcodec v210 -ac 2 'DeckLink Duo (4)' Keep track of the PTS of the first frame received, so that when we enable start playback we can provide that value to the decklink driver. Thanks to Marton Balint for review and suggestion to use AV_NOPTS_VALUE rather than zero for the initial value. Signed-off-by: Devin Heitmueller <dheitmueller@ltnglobal.com> --- libavdevice/decklink_common.h | 1 + libavdevice/decklink_enc.cpp | 8 ++++++-- 2 files changed, 7 insertions(+), 2 deletions(-)