[FFmpeg-devel] [PATCH] avformat/mpegts: parse large PMTs with multiple tables

[Michael Niedermayer]

On Mon, Jun 11, 2018 at 12:43:31AM -0700, Aman Gupta wrote:
> From: Aman Gupta <aman at tmm1.net>
> 
> In 9152c1e4955, the mpegts parser was taught how to parse
> PMT sections which contained multiple tables. That commit
> fixed parsing of PMT packets from some cable providers,
> which included a special SCTE table (0xc0) before the
> standard program map table (0x2).
> 
> Sometimes, however, the combined 0xc0 and 0x2 tables are
> larger than a single TS packet (188 bytes). The mpegts parser
> already attempts to parse sections which span multiple packets,
> but still assumed that the split section only contained one
> table.
> 
> This patch fixes parsing of such a sample[1].
> 
> Before:
> 
>     Input #0, mpegts, from 'combined-pmt-tids-split.ts':
>       Duration: 00:00:01.26, start: 39188.931756, bitrate: 597 kb/s
>       Program 1
>       No Program
>         Stream #0:0[0xeff]: Audio: ac3, 48000 Hz, mono, fltp, 64 kb/s
>         Stream #0:1[0xefd]: Audio: mp3, 0 channels, fltp
>         Stream #0:2[0xefe]: Unknown: none
> 
> After:
> 
>     Input #0, mpegts, from 'combined-pmt-tids-split.ts':
>       Duration: 00:00:01.27, start: 39188.931756, bitrate: 589 kb/s
>       Program 1
>         Stream #0:0[0xefd]: Video: h264 ([27][0][0][0] / 0x001B), none, 59.94 fps, 59.94 tbr, 90k tbn, 180k tbc
>         Stream #0:1[0xefe](eng): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, stereo, fltp, 384 kb/s
>         Stream #0:2[0xeff](spa): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, mono, fltp, 64 kb/s
>         Stream #0:3[0xf00]: Data: scte_35
>         Stream #0:4[0xf01]: Unknown: none (ETV1 / 0x31565445)
>         Stream #0:5[0xf02]: Unknown: none (ETV1 / 0x31565445)
>         Stream #0:6[0xf03]: Unknown: none ([192][0][0][0] / 0x00C0)
> 
> With the patch, the PMT is parsed correctly so the streams are
> created in the correct order, are associated with "Program 1",
> and their codecs are set correctly.
> 
> [1] https://s3.amazonaws.com/tmm1/combined-pmt-tids-split.ts
> 
> Signed-off-by: Aman Gupta <aman at tmm1.net>
> ---
>  libavformat/mpegts.c | 1 +
>  1 file changed, 1 insertion(+)

with this change section_h_size becomes almost a local variable
is that intended ?

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The worst form of inequality is to try to make unequal things equal.
-- Aristotle
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