[FFmpeg-devel] [PATCH] libavformat/mpegts.c: fix hardcoded 5-bytes skip for metadata streams.

[Anton Khirnov]

Quoting toots at rastageeks.org (2023-06-20 07:09:33)
> From: Romain Beauxis <toots at rastageeks.org>
> 
> Before the introduction of AV_CODEC_ID_TIMED_ID3 for timed_id3 metadata streams
> in mpegts (commit 4a4437c0fbc8f7afe0c533070395a42e56b4ee75), AV_CODEC_ID_SMPTE_KLV
> was the only existing codec for metadata.
> 
> It seems that this codec has a 5-bytes metadata header[1] that, for some reason,
> was always skipped when decoding data packets.
> 
> However, when working with a AV_CODEC_ID_TIMED_ID3 streams, this results in the
> 5 first bytes of the payload being cut-off, which includes essential informations
> such as the ID3 tag version.
> 
> This patch fixes the issue by keeping the 5-bytes skip only for AV_CODEC_ID_SMPTE_KLV
> streams.
> 
> To test:
> 1. download this file: https://www.dropbox.com/s/jy8sih3pe8qskxb/bla.ts?dl=1
> 
> This file was download from: http://playertest.longtailvideo.com/adaptive/wowzaid3/playlist.m3u8
> 
> 2. run this command:
>   ffprobe -show_streams -select_streams 0 -show_packets -show_private_data \
>           -show_data /path/to/bla.ts
> 
> Before:
> [PACKET]
> codec_type=data
> stream_index=0
> pts=494646418
> pts_time=5496.071311
> dts=494646418
> dts_time=5496.071311
> duration=N/A
> duration_time=N/A
> size=21
> pos=482784
> flags=K__
> data=
> 00000000: 0000 0000 1054 4954 3200 0000 0600 0003  .....TIT2.......
> 00000010: 7465 7374 00                             test.
> 
> After:
> [PACKET]
> codec_type=data
> stream_index=0
> pts=494646418
> pts_time=5496.071311
> dts=494646418
> dts_time=5496.071311
> duration=N/A
> duration_time=N/A
> size=26
> pos=482784
> flags=K__
> data=
> 00000000: 4944 3304 0000 0000 0010 5449 5432 0000  ID3.......TIT2..
> 00000010: 0006 0000 0374 6573 7400                 .....test.

A FATE test for this would be nice.

-- 
Anton Khirnov