Partially broken mp4 clip fails to encode.

[silicontrip]

Hi Steinar,

I have another curly one for you. I have an mp4 clip which the only way I could get it to process (in any transcoder) was to perform a full re-encode in ffmpeg first. Not even a stream copy would allow it to encode.

It appeared to be processing, but only produced a 233k file containing a few frames.
I'm not sure about the legality of sharing this particular clip.

Is there anything I can do here to help you investigate why this clip won't process?

This is the output from mediainfo

Code: Select all

General
Complete name                            : 1_04_R_08092016090000PM.mp4
Format                                   : AVC
Format/Info                              : Advanced Video Codec
File size                                : 220 MiB

Video
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline@L2
Format settings, CABAC                   : No
Format settings, ReFrames                : 2 frames
Format settings, GOP                     : M=1, N=50
Width                                    : 352 pixels
Height                                   : 288 pixels
Display aspect ratio                     : 1.222
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive

ffmpeg does report this problem with the original file when converting;

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[h264 @ 0x7fe3eb011e00] corrupted macroblock 7 16 (total_coeff=-1)    
[h264 @ 0x7fe3eb011e00] error while decoding MB 7 16
[h264 @ 0x7fe3eb011e00] concealing 86 DC, 86 AC, 86 MV errors in P frame

[admin]

This is hardly a FFAStrans bug, is it...?

Do you have another healthy file from the same source with the exact same technical specs. (except length/size) ?

-steinar

[silicontrip]

That depends on what is the expected output.
I would've assumed one of the following;
1) be able to handle the media file similar to ffmpeg
2) report an error that the clip was not able to be converted

However, FFAStrans claims that it has encoded it successfully, the xd-cam processor took a long time to encode and counted up to 2500 (I assume this is the duration of the clip) so everything looked ok but produced a file with only 1 or 2 frames.

I wouldn't mind working out why this file is causing problems, because not even re-muxing the file in ffmpeg resolved the issue.
Thanks
Mark

[admin]

It would be easier to help you out if you sent me the file so I could investigate. Does ffmpeg report en error showing that it could not encode, or is it just throwing warnings?

-steinar

[silicontrip]

ffmpeg is giving warnings and re-encoding the file successfully.
Do you have a dropbox of some sort? I don't think I'm allowed to make the file publicly available.

[admin]

How big is the file?

[silicontrip]

220meg

[admin]

Thanks for sending the file. However, I cannot get it to NOT decode/encode. I have tried with the "A/V Media"-decoder in both "Intelligent" and "Full decode" mode. I've also tried submitting directly to an encoder. Everything works as expected except it's having problem retrieving the length in all cases. So i get two files that's 41:50 long and one that's 43:35. But the last one freeze frame from 41:50. I've also had no problems creating a new file through stream copy as mkv but it failed at mp4. Anyway, I wonder if you might have a special workflow that makes this particular file fail? If so, can you please send it?

-steinar

[silicontrip]

I have just one workflow which I'm refining for all the different input files I've encountered.

Hopefully this is enough to test it with.

Harris Ingest.zip

(4.68 KiB) Downloaded 544 times

[silicontrip]

Although since I've been refining it, that's probably not the workflow I originally tested it with.
I've also just upgraded to 0.7.7 so I'm testing it again and will let you know the results.