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

[toots at rastageeks.org]

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.

---
 libavformat/mpegts.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index fb8b0bf8fd..0b3edda817 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -1305,7 +1305,7 @@ skip:
                     p += sl_header_bytes;
                     buf_size -= sl_header_bytes;
                 }
-                if (pes->stream_type == 0x15 && buf_size >= 5) {
+                if (pes->st->codecpar->codec_id == AV_CODEC_ID_SMPTE_KLV && buf_size >= 5) {
                     /* skip metadata access unit header */
                     pes->pes_header_size += 5;
                     p += 5;
-- 
2.39.2 (Apple Git-143)