Help repairing corrupt mp4 files?

[ttremblay]

I've got a few fairly large (1-5GB) .mp4 files from xsplit from an event I recorded. They won't open in VLC or PotPlayer and attempting to reencode them with ffmpeg yields a "unspecified pixel format" error. I really need these recordings and any help would be greatly appreciated.

I saw a few threads about editing the header of the .mp4 file, but after looking at it in a hex editor, I don't know where the header ends and the body begins.

[JVRaines]

If you're able to throw money instead of time at the problem, try mp4repair.org.

[ttremblay]

If you're able to throw money instead of time at the problem, try mp4repair.org.

Unfortunately, that would cost me an absurd amount of money. I'm willing to put in the time.

[JVRaines]

When you run FFmpeg, have you tried specifying the appropriate pixel format? You should be able to glean it from other MP4 files that work (if you have any).

[ttremblay]

When you run FFmpeg, have you tried specifying the appropriate pixel format? You should be able to glean it from other MP4 files that work (if you have any).

I'm not sure what the pixel format is, or the syntax to do so in ffmpeg. I've attached a MediaInfo screenshot from a non-corrupt file from the same session. My best guess is yuv420.

[Baldrick]

Have you tried run them through ffmpeg?

c:\program\ffmpeg -i c:\video\video.mp4 -vcodec copy -acodec copy c:\video\newvideo.mp4

And see if you get any errors?


You could also try video repair tool. Try the trial(repair half video) and see if you get anything at all. You choose a working mp4 and the broken one.

[ttremblay]

Have you tried run them through ffmpeg?

c:\program\ffmpeg -i c:\video\video.mp4 -vcodec copy -acodec copy c:\video\newvideo.mp4

And see if you get any errors?


You could also try video repair tool. Try the trial(repair half video) and see if you get anything at all. You choose a working mp4 and the broken one.

Yup. Tried that. ffmpeg says there's an unspecified pixel format and I don't know how to specify it.

[Cornucopia]

Use ffprobe on a known good file to use as a reference of what parameters to use.

Scott

[ttremblay]

Use ffprobe on a known good file to use as a reference of what parameters to use.

Scott

ffprobe on a known good video returns:

 Metadata:
   major_brand     : isom
   minor_version   : 512
   compatible_brands: isomiso2avc1mp41
 Duration: 01:00:02.17, start: 0.000000, bitrate: 4528 kb/s
   Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 98 kb/s (default)
   Metadata:
     handler_name    : SoundHandler
   Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 4422 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
   Metadata:
     handler_name    : VideoHandler

So I tried the following command based on this link:

ffmpeg -f rawvideo -vcodec rawvideo -s 1280x720 -r 30 -pix_fmt yuv420p -i inputfile.mp4 -c:v libx264 -preset medium -qp 23 output.mp4

And got a massive file of only static.

[JVRaines]

What happens if you leave out all the rawvideo stuff and just specify pix_fmt as an input option? I.e.

ffmpeg -pix_fmt yuv420p -i inputfile.mp4 -c:v libx264 -preset medium -qp 23 output.mp4

[WazaKrash]

Maybe you can use it with File Repair.

Or when I have that sort of problem, I convert the file in another format (avi, mp4, whatever you want) sometimes you can finally play the video after the conversion.

[ttremblay]

What happens if you leave out all the rawvideo stuff and just specify pix_fmt as an input option? I.e.

ffmpeg -pix_fmt yuv420p -i inputfile.mp4 -c:v libx264 -preset medium -qp 23 output.mp4

I get this error:

Option pixel_format not found.

[ttremblay]

Maybe you can use it with File Repair.

Or when I have that sort of problem, I convert the file in another format (avi, mp4, whatever you want) sometimes you can finally play the video after the conversion.

File repair says "No data to recover detected" on both the corrupted and healthy files.

[JVRaines]

What happens if you leave out all the rawvideo stuff and just specify pix_fmt as an input option? I.e.

ffmpeg -pix_fmt yuv420p -i inputfile.mp4 -c:v libx264 -preset medium -qp 23 output.mp4

I get this error:

Option pixel_format not found.

The option is pix_fmt, not pixel_fmt. Or is the misspelling in the error message?

[ttremblay]

What happens if you leave out all the rawvideo stuff and just specify pix_fmt as an input option? I.e.

ffmpeg -pix_fmt yuv420p -i inputfile.mp4 -c:v libx264 -preset medium -qp 23 output.mp4

I get this error:

Option pixel_format not found.

The option is pix_fmt, not pixel_fmt. Or is the misspelling in the error message?

It's misspelling the error message, I'm running the command exactly as above.

[JVRaines]

Can you post the entire output of ffprobe?

ffprobe badfile.mp4

[ttremblay]

Can you post the entire output of ffprobe?

ffprobe badfile.mp4

ffprobe won't run on the corrupted file. It just sits there until i press ^C.

[JVRaines]

Does adding the -loglevel debug option before the filename produce anything?

Hate to say it, but your options are looking to be either paying someone else to recover the files, if possible, or studying the MPEG-4 Part 10 and Part 14 specifications until you have learned enough to hack the files in a byte editor.

[ttremblay]

Does adding the -loglevel debug option before the filename produce anything?

Hate to say it, but your options are looking to be either paying someone else to recover the files, if possible, or studying the MPEG-4 Part 10 and Part 14 specifications until you have learned enough to hack the files in a byte editor.

I just tried the tool mentioned in this stackoverflow question: http://stackoverflow.com/questions/23202611/repairing-a-corrupt-mp4-video-file

I was able to get a .h264 and a .acc file that both play fine in PotPlayer. Now I need to figure out how to combine the two into a .mp4 file with ffmpeg. Any ideas?

[JVRaines]

That's great news! And way quicker than becoming an MP4 expert. Try this:

ffmpeg -i myvideo.h264 -i myaudio.aac -c copy -map 0:v -map 1:a mynewfile.mp4

[ttremblay]

That's great news! And way quicker than becoming an MP4 expert. Try this:

ffmpeg -i myvideo.h264 -i myaudio.aac -c copy -map 0:v -map 1:a mynewfile.mp4

Malformed AAC bitstream detected: use the audio bitstream filter 'aac_adtstoasc' to fix it ('-bsf:a aac_adtstoasc' option with ffmpeg)

I'm not sure where to put this option.

[JVRaines]

You can put it after the copy option.

[ttremblay]

You can put it after the copy option.

Ok. That worked. Except i get an error saying "pts has no value". The file still finished, but the audio and video are drastically offset.

[JVRaines]

You may need to specify -fflags +genpts before the input file (before the -i) that's causing the problem.

[ttremblay]

Before the video input or the audio input?

[ttremblay]

Before the video input or the audio input?

ffmpeg.exe -fflags +genpts -i "G:\recover tool\recovered.h264" -i "G:\recover tool\recovered.aac" -c copy -bsf:a aac_adtstoasc -map 0:v -map 1:a "G:\NE FIRST UMass District\2015-03-14_075202579_recovered_2.mp4"

This line still causes the "pts has no value" error.

[JVRaines]

I have no idea because you didn't post the output. I would guess audio because that's where you got the error message.