[mythtv] Mythtranscode HLS/AVF heavily distorted output

John Pilkington J.Pilk at tesco.net
Sun Jul 26 14:30:37 UTC 2015


On 26/07/15 11:31, John Pilkington wrote:
> On 26/07/15 10:59, John Pilkington wrote:
>> On 26/07/15 08:31, William Wilhelm wrote:
>>
>>>
>>> On 25 July 2015 7:32:31 pm William Wilhelm <will at wilhelm.com.au> wrote:
>>>
>>
>>>>
>>>> On 25 July 2015 7:11:43 pm John Pilkington <J.Pilk at tesco.net> wrote:
>>>>
>>>> > On 25/07/15 08:48, William Wilhelm wrote:
>>>> > > Ever since 0.27 -> 0.28, mythtranscode --avf/--hls has been giving
>>>> very
>>>> > > distorted output for transcodings of FTA recordings here in
>>>> Australia.
>>>> > > Prebuilt "nightlies" from Mythbuntu and my own weekly builds from
>>>> master
>>>> > > both experience this issue. Audio is unaffected.
>>>> > >
>>>> > > All channels are affected except for ABC News 24 and SBS 2.
>>>> > > To describe heavily distorted more: http://i.imgur.com/hfgrn2i.png.
>>
>>>> > > Output for a non affected recording (from ABC News 24 or SBS 2) has
>>>> > > similar output which I can provide if needed.
>>>> > > Have several samples of affected and non-affected recordings that
>>>> I can
>>>> > > share.
>>>> > >
>>>> > > Thanks,
>>>> > > Will
>>>> >
>>>> > Have you tried doing a lossless transcode (-m) first?  It might
>>>> discard
>>>> > all the streams that ffprobe dislikes.
>>>> >
>>>> > John P
>>
>>
>>>> I have just tried this now, and the lossless transcode does strip the
>>>> irrelevant streams, but the --avf transcode is still distorted.
>>>>
>>
>>  > I spent some time reverting commits affecting external/FFmpeg and got
>>  > all the way back to FFmpeg 1.2.6, the version that works in 0.27. I
>> have
>>  > also reverted programs/mythtranscode back to 0.27 code. The distortion
>>  > still happens.
>>  >
>>  > Leads me to think it's not an FFmpeg issue.
>>  >
>>
>> I have not used this before, but I see similar effects on the shortest
>> recording I have - a UKIP PPB from itv in the UK, SD converted from .ts
>> to .mpg  It's rather like a bad line-hold setting.   Playback tried by
>> vlc and SMplayer.
>>
>> [john at HP_Box RecsSG1]$ mythtranscode --avf -i 1003_20150402171800.mpg -o
>> testPPB.avf
>> 2015-07-26 10:06:23.180406 C  mythtranscode version: master
>> [v0.28-pre-2683-g7f68683] www.mythtv.org
>> 2015-07-26 10:06:23.180453 C  Qt version: compile: 4.8.5, runtime: 4.8.5
>> ========
>> 2015-07-26 10:06:23.700943 E  FilterManager: Failed to load filter
>> 'yadif', no such filter exists
>> ========
> And now *two* versions of output stream analysis:
>
> [john at HP_Box RecsSG1]$ ffmpeg -i testPPB.avf
> ffmpeg version 2.6.3 Copyright (c) 2000-2015 the FFmpeg developers
>    built with gcc 4.8.3 (GCC) 20140911 (Red Hat 4.8.3-9)
>
>      Stream #0:0[0x100]: Video: h264 (Constrained Baseline)
> ([27][0][0][0] / 0x001B), yuv420p, 480x272, 25 fps, 25 tbr, 90k tbn, 50 tbc
>      Stream #0:1[0x101]: Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000
> Hz, stereo, fltp, 30 kb/s
> ===========
>
> [john at HP_Box RecsSG1]$ mythffmpeg -i testPPB.avf
> ffmpeg version 2.3.1 Copyright (c) 2000-2014 the FFmpeg developers
>    built on Feb 19 2015 23:55:22 with gcc 4.8.2 (GCC) 20140120 (Red Hat
> 4.8.2-16)
>
> Input #0, mpegts, from 'testPPB.avf':
>    Duration: 00:03:58.40, start: 0.001000, bitrate: 816 kb/s
>      Stream #0:0[0x100]: Video: h264 (Constrained Baseline), yuv420p,
> 480x272, 25 fps, 25 tbr, 90k tbn, 50 tbc
>      Stream #0:1[0x101]: Audio: aac, 48000 Hz, stereo, fltp, 68 kb/s
>
> ==========
>> I'll try it with a current *buntu master, sometime.

I did, on a raw SD .ts recording - again from itv.  The effect, and the 
o/p stream analyses, are very similar.

2015-07-26 14:20:57.729555 C  mythbackend version: master 
[v0.28-pre-2986-g004b87d] www.mythtv.org
2015-07-26 14:20:57.729584 C  Qt version: compile: 5.2.1, runtime: 5.2.1

>>
>> John
>>
>>



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