[FFmpeg-devel] [PATCH 1/6] avformat/mpegtsenc: fix incorrect PCR selection with multiple programs

[Marton Balint]

On Fri, 9 Aug 2019, Andreas Håkon wrote:

> Hi Marton,
>
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On Thursday, 8 de August de 2019 23:27, Marton Balint <cus at passwd.hu> wrote:
>
>> The MPEG-TS muxer had a serious bug related to the use of multiple programs:
>> in that case, the PCR pid selection was incomplete for all services except one.
>> This patch solves this problem and selects a stream to become PCR for each
>> service, preferably the video stream.
>>
>> This patch also moves pcr calculation attributes to MpegTSWriteStream from
>> MpegTSService. PCR is a per-stream and not per-service thing, so it was
>> misleading to refer to it as something that is per-service.
>>
>> Also remove *service from MpegTSWriteStream because a stream can belong to
>> multiple services so it was misleading to select one for each stream.
>>
>> You can check the result with this example command:
>>
>> ./ffmpeg -loglevel verbose -y -f lavfi -i \
>> "testsrc=s=64x64:d=10,split=2[out0][tmp1];[tmp1]vflip[out1];sine=d=10,asetnsamples=1152[out2]" \
>> -flags +bitexact -fflags +bitexact -sws_flags +accurate_rnd+bitexact \
>> -codec:v libx264 -codec:a mp2 -pix_fmt yuv420p \
>> -map '0:v:0' \
>> -map '0:v:1' \
>> -map '0:a:0' \
>> -program st=0:st=2 -program st=1:st=2 -program st=2 -program st=0 -f mpegts out.ts
>
> I recommend this small change to the test:
>
> ./ffmpeg -loglevel verbose -y -f lavfi -i \
>  "testsrc=s=64x64:d=10,split=2[out0][tmp1];[tmp1]vflip[out1];sine=d=10,asetnsamples=1152[out2]" \
>  -flags +bitexact -fflags +bitexact -sws_flags +accurate_rnd+bitexact  \
>  -codec:v libx264 -r:v:0 1 -r:v:1 25 -b:v:0 1000k -b:v:1 1500k -pix_fmt yuv420p \
>  -codec:a mp2 \
>  -map '0:v:0' \
>  -map '0:v:1' \
>  -map '0:a:0' \
>  -program st=0:st=2 -program st=1:st=2 -program st=2 -program st=0 \
>  -f mpegts -muxrate 1M out.ts
>
> CBR it's required and the use of different bitrates it's desirable.
>
>> You should now see this:
>>
>> [mpegts @ 0x37505c0] service 1 using PCR in pid=256
>> [mpegts @ 0x37505c0] service 2 using PCR in pid=257
>> [mpegts @ 0x37505c0] service 3 using PCR in pid=258
>> [mpegts @ 0x37505c0] service 4 using PCR in pid=256
>
> Updated output:
>
> [mpegts @ 0x33473c0] service 1 using PCR in pid=256, pcr_period=20ms
> [mpegts @ 0x33473c0] service 2 using PCR in pid=257, pcr_period=20ms
> [mpegts @ 0x33473c0] service 3 using PCR in pid=258, pcr_period=20ms
> [mpegts @ 0x33473c0] service 4 using PCR in pid=256, pcr_period=20ms
> [mpegts @ 0x33473c0] muxrate 1000000, sdt every 332, pat/pmt every 66 pkts

This output requires patch 5, so the commit message of _this_ patch should 
refer to the old output.

Regards,
Marton