.flv file video not playing, listed as frame height and width 0

[Xirix]

Was wondering if anyone could take a look at this for me (Attached two posts down)

This is a segment of an old twitch stream, back then if you downloaded from twitch it would grab in 30 minute flash video chunks, I just noticed this one, although it finished downloading and the audio plays, the video doesn't, and the file lists the frame height and width as 0.

The size of the file looks about right compared to the other chunks, so I'm wondering if the video is just borked and I'm out of luck, or if the video data is there, but the .flv didn't write properly and it needs editing/converting to make it work.

[DB83]

Did you upload that to Archive.org since it has no plays etc.Mind you that could be due to the removal of flash video support by Adobe some weeks ago.Better to find some other way to share it (as long as it is not illegal) such as direct attachment in this topic.

[Xirix]

Ah, I had uploaded it there for convenience, but I see that the allowed size for attachments on here is actually enough, oops. I'll up it here now.

[DB83]

Hardly convenient when it has already been taken down for whatever reason. (and the forum does support attachments up to 500 mb)

But I did download it and there is no video. Just audio. (AVC in a .flv container ? I think not)


Better to compare that with one from the same source that does play.

[Xirix]

Yes, I know, that's why I replied with it as an attachment and removed it from archive.org

The other ones that 'do' play say they have AVC video according to mediainfo, they are also .flvs, with this weird broken one mediainfo also is able to find the video's FPS info, just no resolution at all.

I don't suppose there's a way to trick it into playing, like can you rewrite the info in the file to say 1280x720 resolution and see if it does anything? Since there's clearly a big block of video in there from the filesize, and I find it weird that the file finished with the audio being able to be played, you'd think if it didn't grab the chunk correctly it just wouldn't play at all.

[Selur]

AVC in a .flv container ? I think not)

Sure, not that uncommon. Attached a sample. A bunch of streaming server used flv as container for avc.
see: https://en.wikipedia.org/wiki/Flash_Video

Since I don't see much of AVC or aac headers in the file my guess is that the stream is either totally broken or encrypted.

[Xirix]

There's no reason it would be encrypted that I can think of so I guess maybe I'm out of luck, ah, a shame. :/ And indeed I did notice that although mediainfo did give some minor info for the video part of the file, the other parts of the stream gave considerably more information for their video segments.

I guess when it downloaded something went wrong, but instead of just giving me a completely guff unreadable file it half-finished, which unfortunately led me to not noticing something was wrong.

Thanks for looking at it, I'll cross my fingers if anyone else has any other ideas but I know this is a shot in the dark.

[DB83]

Well you have little to lose right now so here is a suggestion. Load a working part of the stream in to a hex editor and this borked version in to another hex editor (or a separate window of the same)

See if you can determine the changes req'd and edit the header accordingly (of course you will have to scroll down to see of there is data and not just a ton of zeros)

[Xirix]

Honestly I wouldn't know where to start with a hex editor, I'm not very good when it comes to code stuff. I had a little look, it looks like there's data there, there's the occasional big block of FF but the working files with video seem to have those too.

[jagabo]

VLC, MPCBE, Potplayer, and SMPlayer are able to play the audio.

[Selur]

Strange, MPC-HC doesn't really play audio here.

[Xirix]

VLC, MPCBE, Potplayer, and SMPlayer are able to play the audio.

Yeah, but I'm trying to get the video playing, not the audio.

[ProWo]

You could try mp4repair.
1) Rename the corrupt file from flv to mp4.
2) Rename a working segment to mp4 too.
3) Download this one: https://www.videohelp.com/download/mp4repair-1.zip
4) Extract to any location and start mp4repair.exe, select 2) as reference file, select 1) as corrupt file, click execute.

[jagabo]

Oops, wrong thread...

[Xirix]

You could try mp4repair.
1) Rename the corrupt file from flv to mp4.
2) Rename a working segment to mp4 too.
3) Download this one: https://www.videohelp.com/download/mp4repair-1.zip
4) Extract to any location and start mp4repair.exe, select 2) as reference file, select 1) as corrupt file, click execute.

No dice on that unfortunately, I'm not sure the program even did anything, it said "done", but the corrupt file had no change in date modified, nor did it make a new file.

[ProWo]

No messages in the program window?
Repeat the procedure with verbose logging.

[DB83]

Whist ,flv and .mp4 are container formats I guess that the format structure is different enough for that repair program to bork.

So, returning to my earlier suggestion, if you are not confident enough to attempt a direct edit of the header in a hex editor I can only suggest you upload a working sample - from the same source - as an attachment and someone may be kind enough to attempt an edit. And as previously stated right now you have little to nothing to lose from this.

[Xirix]

Even with verbose logging nothing's showing up no, I guess it doesn't like the file.

And sure, good idea, I've attached a working chunk of the stream, I'll cross my fingers if anyone can figure out anything, thanks!

[cholla]

give this link a read:
https://forum.videohelp.com/threads/368428-convert-avc-to-mp4

[jagabo]

I've attached a working chunk of the stream

In a hex editor you can see that there is missing metadata at the start of the non-working file. I somewhat blindly pasted the first ~680000 bytes of the working file over the same part of the non-working file. The result was a file the played (VLC) a few seconds of the working video then skipped ahead about 2 minutes into the non-working video and played to the end(?).


[Attachment 66483 - Click to enlarge]

Pasting a smaller amount would probably get you more of the start of the non-working video.

Pasting about 0x5000 bytes (~20000 bytes) gave a file that plays pretty much from the start. Attached is the first 36 seconds of the "fixed" video remuxed into an mp4.

[Xirix]

I've attached a working chunk of the stream

In a hex editor you can see that there is missing metadata at the start of the non-working file. I somewhat blindly pasted the first ~680000 bytes of the working file over the same part of the non-working file. The result was a file the played (VLC) a few seconds of the working video then skipped ahead about 2 minutes into the non-working video and played to the end(?).


[Attachment 66483 - Click to enlarge]

Pasting a smaller amount would probably get you more of the start of the non-working video.

Pasting about 0x5000 bytes (~20000 bytes) gave a file that plays pretty much from the start. Attached is the first 36 seconds of the "fixed" video remuxed into an mp4.

Oh wow, this looks good, thank you very much, you managed to get the entire thing behaving? If you upload the full thing I'll watch it through to confirm.

[jagabo]

All but the first few second. Pasting the first 0x4900 bytes of the working video onto the non working video:

[Xirix]

All but the first few second. Pasting the first 0x4900 bytes of the working video onto the non working video:

That's just perfect, thank you so much!

[DB83]

Harry (jagabo) Potter strikes again !

[ProWo]

In a hex editor you can see that there is missing metadata at the start of the non-working file. I somewhat blindly pasted the first ~680000 bytes of the working file over the same part of the non-working file. The result was a file the played (VLC) a few seconds of the working video then skipped ahead about 2 minutes into the non-working video and played to the end(?).
Pasting a smaller amount would probably get you more of the start of the non-working video.
Pasting about 0x5000 bytes (~20000 bytes) gave a file that plays pretty much from the start. Attached is the first 36 seconds of the "fixed" video remuxed into an mp4.

just out of curiosity: which hex editor did you use?

[jagabo]

just out of curiosity: which hex editor did you use?

HxD Hex Editor
https://mh-nexus.de/en/programs.php

[ProWo]

just out of curiosity: which hex editor did you use?

HxD Hex Editor
https://mh-nexus.de/en/programs.php

Thx

[jagabo]

By the way, I also tried pre-pending (rather than replacing) 0x4900 bytes from the good file to the bad file. That gave a video that played all the way from start to end.