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[FFmpeg-devel] libavformat/mov: Expose Quicktime poster_time value as metadata TAG.

Message ID pull.21.ffstaging.FFmpeg.1643844144096.ffmpegagent@gmail.com
State New
Headers show
Series [FFmpeg-devel] libavformat/mov: Expose Quicktime poster_time value as metadata TAG. | expand

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Commit Message

Aman Karmani Feb. 2, 2022, 11:22 p.m. UTC 
From: Bryce Chester Newman <bryce.newman@gettyimages.com>

I need the ability to derive the poster time found in the mvhd, so I can
use that value to create a thumbnail from ffmpeg. More details can be
found here
https://www.mail-archive.com/ffmpeg-user@ffmpeg.org/msg30003.html

Signed-off-by: Bryce Chester Newman <bryce.newman@gettyimages.com>
---
    libavformat/mov: Expose Quicktime poster_time value as metadata TAG.
    
    I need the ability to derive the poster time found in the mvhd, so I can
    use that value to create a thumbnail from ffmpeg. More details can be
    found here
    https://www.mail-archive.com/ffmpeg-user@ffmpeg.org/msg30003.html
    
    Signed-off-by: Bryce Chester Newman bryce.newman@gettyimages.com

Published-As: https://github.com/ffstaging/FFmpeg/releases/tag/pr-ffstaging-21%2Fbrycechesternewman%2Fpatch-poster-time-tag-v1
Fetch-It-Via: git fetch https://github.com/ffstaging/FFmpeg pr-ffstaging-21/brycechesternewman/patch-poster-time-tag-v1
Pull-Request: https://github.com/ffstaging/FFmpeg/pull/21

 libavformat/mov.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)


base-commit: 2e82c610553efd69b4d9b6c359423a19c2868255

Comments

Bryce Newman July 12, 2022, 5:20 p.m. UTC | #1 
Hello,
Can someone please have a look at this patch request?
Thank you in advance.
Bryce
    
    

Bryce Chester Newman | Principal Developer
 
p: +12069255045 | 



From: Bryce Chester Newman <ffmpegagent@gmail.com>
Date: Wednesday, February 2, 2022 at 4:22 PM
To: ffmpeg-devel@ffmpeg.org <ffmpeg-devel@ffmpeg.org>
Cc: Bryce Newman <bryce.newman@gettyimages.com>, Bryce Newman <bryce.newman@gettyimages.com>
Subject: [EXTERNAL] [PATCH] [PATCH] libavformat/mov: Expose Quicktime poster_time value as metadata TAG.
From: Bryce Chester Newman <bryce.newman@gettyimages.com>

I need the ability to derive the poster time found in the mvhd, so I can
use that value to create a thumbnail from ffmpeg. More details can be
found here
https://www.mail-archive.com/ffmpeg-user@ffmpeg.org/msg30003.html

Signed-off-by: Bryce Chester Newman <bryce.newman@gettyimages.com>
---
    libavformat/mov: Expose Quicktime poster_time value as metadata TAG.

    I need the ability to derive the poster time found in the mvhd, so I can
    use that value to create a thumbnail from ffmpeg. More details can be
    found here
    https://www.mail-archive.com/ffmpeg-user@ffmpeg.org/msg30003.html

    Signed-off-by: Bryce Chester Newman bryce.newman@gettyimages.com

Published-As: https://github.com/ffstaging/FFmpeg/releases/tag/pr-ffstaging-21%2Fbrycechesternewman%2Fpatch-poster-time-tag-v1
Fetch-It-Via: git fetch https://github.com/ffstaging/FFmpeg pr-ffstaging-21/brycechesternewman/patch-poster-time-tag-v1
Pull-Request: https://github.com/ffstaging/FFmpeg/pull/21

 libavformat/mov.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index a80fcc1606..3d36f6563f 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1487,6 +1487,7 @@ static int mov_read_mvhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
     int i;
     int64_t creation_time;
+    int32_t poster_time;
     int version = avio_r8(pb); /* version */
     avio_rb24(pb); /* flags */

@@ -1525,12 +1526,21 @@ static int mov_read_mvhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)

     avio_rb32(pb); /* preview time */
     avio_rb32(pb); /* preview duration */
-    avio_rb32(pb); /* poster time */
+    poster_time = avio_rb32(pb); /* poster time */
     avio_rb32(pb); /* selection time */
     avio_rb32(pb); /* selection duration */
     avio_rb32(pb); /* current time */
     avio_rb32(pb); /* next track ID */

+    av_log(c->fc, AV_LOG_TRACE, "poster_time = %i, time_scale = %i\n", poster_time, c->time_scale);
+    if(poster_time && c->time_scale && c->time_scale > 0) {
+        char buffer[32];
+        float poster_time_location = (float)poster_time / c->time_scale;
+        snprintf(buffer, sizeof(buffer), "%.2f", poster_time_location);
+        /* This will appear as a TAG in the format section of FFProbe output using -show_format */
+        av_dict_set(&c->fc->metadata, "poster_time", buffer, 0);
+    }
+
     return 0;
 }


base-commit: 2e82c610553efd69b4d9b6c359423a19c2868255
--
ffmpeg-codebot
Anton Khirnov July 13, 2022, 11:19 a.m. UTC | #2 
Quoting Bryce Newman (2022-07-12 19:20:17)
> Hello,
> Can someone please have a look at this patch request?
> Thank you in advance.

Metadata is intended for user-presentable strings, not structured
values.

The least bad way of exporting this I can think of is adding a
demuxer-private AV_OPT_FLAG_EXPORT option.

Also, avoid floating point - it is inexact.
Bryce Newman July 19, 2022, 5:37 p.m. UTC | #3 
Thank you for the feedback Anton.

I only care about this value being displayed when calling ffprobe, so does it make sense to do this in ffprobe.c or could this be added to the existing mov.c demuxer?

“demuxer-private AV_OPT_FLAG_EXPORT” is new territory for me, so was wondering if there some example of how the similar values could be added to allow ffprobe to stdout the value – perhaps some existing commit request that shows how to make use of exposing values using AV_OPT_FLAG_EXPORT?

Thank you for your time.


From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> on behalf of Anton Khirnov <anton@khirnov.net>
Date: Wednesday, July 13, 2022 at 5:19 AM
To: Bryce Chester Newman <ffmpegagent@gmail.com>, ffmpeg-devel@ffmpeg.org <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [EXTERNAL] [PATCH] [PATCH] libavformat/mov: Expose Quicktime poster_time value as metadata TAG.
Quoting Bryce Newman (2022-07-12 19:20:17)
> Hello,
> Can someone please have a look at this patch request?
> Thank you in advance.

Metadata is intended for user-presentable strings, not structured
values.

The least bad way of exporting this I can think of is adding a
demuxer-private AV_OPT_FLAG_EXPORT option.

Also, avoid floating point - it is inexact.

--
Anton Khirnov
diff mbox series

Patch

diff --git a/libavformat/mov.c b/libavformat/mov.c
index a80fcc1606..3d36f6563f 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1487,6 +1487,7 @@  static int mov_read_mvhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
     int i;
     int64_t creation_time;
+    int32_t poster_time;
     int version = avio_r8(pb); /* version */
     avio_rb24(pb); /* flags */
 
@@ -1525,12 +1526,21 @@  static int mov_read_mvhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
     avio_rb32(pb); /* preview time */
     avio_rb32(pb); /* preview duration */
-    avio_rb32(pb); /* poster time */
+    poster_time = avio_rb32(pb); /* poster time */
     avio_rb32(pb); /* selection time */
     avio_rb32(pb); /* selection duration */
     avio_rb32(pb); /* current time */
     avio_rb32(pb); /* next track ID */
 
+    av_log(c->fc, AV_LOG_TRACE, "poster_time = %i, time_scale = %i\n", poster_time, c->time_scale);
+    if(poster_time && c->time_scale && c->time_scale > 0) {
+        char buffer[32];
+        float poster_time_location = (float)poster_time / c->time_scale;
+        snprintf(buffer, sizeof(buffer), "%.2f", poster_time_location);
+        /* This will appear as a TAG in the format section of FFProbe output using -show_format */
+        av_dict_set(&c->fc->metadata, "poster_time", buffer, 0);
+    }
+
     return 0;
 }