[mythtv] Mythtranscode HLS/AVF heavily distorted output

John Pilkington J.Pilk at tesco.net
Sun Jul 26 10:31:28 UTC 2015


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.
>
> John
>
>
>
> _______________________________________________
> mythtv-dev mailing list
> mythtv-dev at mythtv.org
> http://lists.mythtv.org/mailman/listinfo/mythtv-dev
> http://wiki.mythtv.org/Mailing_List_etiquette
> MythTV Forums: https://forum.mythtv.org
>



More information about the mythtv-dev mailing list