avformat/mpegts: correctly skip TP_extra_header in m2ts

instead of just resyncing and skipping a bunch of TS packets, leading to
a loss of frames.

Before this, a stray byte with the value of 0x47 in TP_extra_header
would throw off the detection of where TS packets start.

A typical file that could cause issues would look like this:

    00000300: 238f 4780 4750 1110 0000 01e0 0000 84c0
                   ^^   ^^
The first four bytes here are TP_extra_header and the actual TS packet
starts at offset 0x304

FFmpeg would try to read a packet at 0x300 but since nothing skips the
4 byte TP_extra_header, find that the first byte is not 0x47 and
immediately go into mpegts_resync, and incorrectly detect the stray 0x47
in the TP_extra_header at 0x302 as the new sync byte.

Fix this by correctly skipping the first 4 bytes if the source packet
is 192 bytes.

Signed-off-by: llyyr <llyyr.public@gmail.com>
Signed-off-by: Hendrik Leppkes <h.leppkes@gmail.com>

0 files changed, 0 insertions, 0 deletions