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Ошибка в mencoder
25.11.2012
03:06
Раздел: Компьютер - Linux - Видео - Mplayer

x264 & ffmpeg mpeg2video errors


0028606

8th June 2009, 21:19


Can anyone suggest a resolution to the errors I'm getting when trying to encode an Mpeg2video source.


I'm using ffmpeg to decode video and feed to x264 for the encode. Any help would be appreciated.


--- Input #0, mpeg, from '/Volumes/Drive 2/Downloads/Tv Shows/U5_8253471A Title 6 (Ch1 - Ch7)/VIDEO_TS/U5_8253471A Title 6 (Ch1 - Ch7).VOB':

Duration: 00:41:48.03, start: 0.053622, bitrate: 6451 kb/s

Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576 [PAR 64:45 DAR 16:9], 8000 kb/s, 25 tbr, 90k tbn, 50 tbc

Stream #0.1[0x81]: Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s

Stream #0.2[0x80]: Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s

Output #0, yuv4mpegpipe, to 'pipe:':

Stream #0.0: Video: rawvideo, yuv420p, 720x576 [PAR 64:45 DAR 16:9], q=2-31, 200 kb/s, 90k tbn, 25 tbc

Stream mapping:

Stream #0.0 -> #0.0

Press [q] to stop encoding

[mpeg2video @ 0x101004400]ac-tex damaged at 7 107.52 bitrate=124417.2kbits/s

[mpeg2video @ 0x101004400]Warning MVs not available

[mpeg2video @ 0x101004400]concealing 45 DC, 45 AC, 45 MV errors

[mpeg2video @ 0x101004400]invalid cbp at 37 29=20.36 bitrate=124417.2kbits/s

[mpeg2video @ 0x101004400]Warning MVs not available

[mpeg2video @ 0x101004400]concealing 45 DC, 45 AC, 45 MV errors

[mpeg2video @ 0x101004400]ac-tex damaged at 24 12.76 bitrate=124417.2kbits/s

[mpeg2video @ 0x101004400]concealing 45 DC, 45 AC, 45 MV errors

[mpeg2video @ 0x101004400]ac-tex damaged at 18 29.48 bitrate=124417.2kbits/s

[mpeg2video @ 0x101004400]concealing 45 DC, 45 AC, 45 MV errors

[mpeg2video @ 0x101004400]ac-tex damaged at 6 206.48 bitrate=124417.2kbits/s

[mpeg2video @ 0x101004400]Warning MVs not available

[mpeg2video @ 0x101004400]concealing 45 DC, 45 AC, 45 MV errors

frame= 1017 fps= 11 q=0.0 Lsize= 617834kB time=40.68 ---


nm

8th June 2009, 23:38

Can anyone suggest a resolution to the errors I'm getting when trying to encode an Mpeg2video source.

There are some errors in the input file. You should either get a correct source or let ffmpeg conceal the errors for you, as it does there.


0028606

9th June 2009, 22:12

Thank you, makes sense now.


froggy1

10th June 2009, 00:15

I've had a similar problem with mplayer/mencoder with perfectly working DVDs. When I force the decoder to mpeg12 (libmpeg12) it works much better for me. You can try to forcing the decoder of ffmpeg to use libmpeg12 (not sure if it's possible and if it's available in ffmpeg since I only use mencoder)


nm

10th June 2009, 00:29

I've had a similar problem with mplayer/mencoder with perfectly working DVDs. When I force the decoder to mpeg12 (libmpeg12) it works much better for me.

Does libavcodec produce incorrect output in those cases? It could also be that it detects, reports and conceals the errors while libmpeg2 doesn't. Generally libavcodec has much better error handling capabilities.


froggy1

10th June 2009, 00:36

Does libavcodec produce incorrect output in those cases? It could also be that it detects, reports and conceals the errors while libmpeg2 doesn't. Generally libavcodec has much better error handling capabilities.


I don't know about libavcodec since I don't use it to generate mpeg1/2 videos. I only force the decoder to mpeg12 (-vc mpeg12) for DVDs and it works much better here on various DVDs. I have one or two DVDs that when used with the ffmpeg2 decoder, they go crazy in spewing such warning messages. Switching over to -vc mpeg12 "fixes" these things. Honestly, I don't know why mplayer switched to ffmpeg2 as default decoder for mpeg2 streams. I remember there was a discussion a while back and ffmpeg2 came as the winner by a very small amount in decoding speed. I guess that's why they set it as default. Dunno, but -vc mpeg12 works much better for me and I have yet to encounter any problems with it, whether visual ones or others


nm

10th June 2009, 01:06

I don't know about libavcodec since I don't use it to generate mpeg1/2 videos.

By libavcodec I meant the ffmpeg2 decoder -- does it produce visually incorrect output compared to libmpeg2 in some case? These error messages usually mean that the decoder has detected a problem and tries to do something about it. Libmpeg2 doesn't have as sophisticated error handling code, so it is more likely that small corruptions in the stream end up as visible artifacts while no error message is printed out.


I only force the decoder to mpeg12 (-vc mpeg12) for DVDs and it works much better here on various DVDs. I have one or two DVDs that when used with the ffmpeg2 decoder, they go crazy in spewing such warning messages. Switching over to -vc mpeg12 "fixes" these things. Honestly, I don't know why mplayer switched to ffmpeg2 as default decoder for mpeg2 streams.

It's actively maintained (and developed further every now and then), and it manages corrupted streams better than other decoders (http://compression.ru/video/codec_comparison/mpeg-2_2006_en.html). This is a nice property in DVB playback, for example.


froggy1

10th June 2009, 01:29

No, I've not encountered any visual problems with ffmpeg2. But, it often gives a lot of warning messages, even on new DVDs which I don't believe are *that* broken. mpeg12 works for me and doesn't spew such messages so I use it. I had one time a problem with ffmpeg2 where somehow it managed to desync the audio/video (which I find very strange O.o). I then encoded the DVD ISO again with the exact same settings, except this time forcing mpeg12 as decoder and the encoding came out flawless


nm

10th June 2009, 11:12

No, I've not encountered any visual problems with ffmpeg2. But, it often gives a lot of warning messages, even on new DVDs which I don't believe are *that* broken.Demuxer can also have an effect on this, especially at the beginning of the stream and when seeking. So "-demuxer lavf" may work better than MPlayer's MPEG-PS demuxer. Then there are new copy protection schemes that could cause corruption.


mpeg12 works for me and doesn't spew such messages so I use it.

Fair enough, but the same errors are still there -- libmpeg2 just doesn't report them. Apparently there is no lavdopts parameter that would disable all the error logging, so to hide the warnings they need to be ripped off afterwards. ;)mplayer dvd://1 -demuxer lavf 2>&1 | grep -v "^\[mpeg2video"


0028606

10th June 2009, 15:54

Solution to the errors is to use the MakeMKV tool spoke about in a previous thread (Excellent bit of software) to back up dvd to .mkv file, then I processed it though ffmpeg and x264.


Resulting in a prefect encode, no errors at all.


froggy1

10th June 2009, 17:28

Demuxer can also have an effect on this, especially at the beginning of the stream and when seeking. So "-demuxer lavf" may work better than MPlayer's MPEG-PS demuxer. Then there are new copy protection schemes that could cause corruption.


True, but it wasn't a demuxer problem. Like I said, switching decoder to mpeg12 for this particular DVD fixed the sync problem. Demuxer was the same in both cases. Shame I didn't ran it one more time with ffmpeg2 to see if I'll get the same problem again so I'm not fully sure if ffmpeg2 was the cause in the first place



Fair enough, but the same errors are still there -- libmpeg2 just doesn't report them. Apparently there is no lavdopts parameter that would disable all the error logging, so to hide the warnings they need to be ripped off afterwards. ;)mplayer dvd://1 -demuxer lavf 2>&1 | grep -v "^\[mpeg2video"


That may be so, but mpeg12 has been the default in mplayer for many years and I have yet to encounter any visual or other problems with it while I did have some problems with ffmpeg2


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