[mythtv] Mythtranscode HLS/AVF heavily distorted output

John Pilkington J.Pilk at tesco.net
Sun Jul 26 09:59:48 UTC 2015


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
========
    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
========
I'll try it with a current *buntu master, sometime.

John





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