Comments (6)
from untrunc.
Hello, have you had a chance to take a look at the videos? I've sent them to you via email a month ago, and still got no answer. Thanks.
from untrunc.
from untrunc.
Hi, first of all - thank you so much for taking time to fix it.
I've tried to fix it myself, as you described - and it really works! The video is fully restored!
But how can i calculate (or at least estimate) the samples count for other videos?
I mean, how can I get the reported number, and if I get it - do I need just to guess the real working number, or is there some way you've got the 24064?
Now I'm very close to get all the videos restored, hope for the last bit of help from you )
Thanks again.
P.S. And what does the -b option do?
from untrunc.
As you know you need a working video with the same characteristics.
if you run untrunc -a good.mp4, you will see each chunk size and offset. In your case the size reported is 288288 which /12 is 24024 (because it is computed from the data written in the atom stsz.
BUT if you check the distance from the offset of an audio packet (for example the first packet is 51799040) and the offset of the next video packet 52087808, it is 288768 (or 24064x12).
This can happens usually for padding (zero or random) , but in your case the additional 480 bytes seems filled with audio samples, can for memory alighment, for page allocations etc.
In your case the extra length is constant, contains audio, the sequence of video/audio is very regular, it could very possibly that I am wrong in interpreting the values (I tried to follo the documentation, but it sucks, when it exists).
Anyway unless you changed the audio parameters it is very likely that all the mp4 have the same problem and solution.
-b instructs untrunc on where the mdat (the atom containing the packets) starts, we only need to point it at the beginning of packet and in our case video packets are easier to spot.
If you want to spot a video packet use a hexeditor (bless for ubuntu works great), search for the ascii text "icpf", and the video packet starts 4 bytes before (works only for your video codec apch, obviously) (you can use the -a options to get the offsets in the good video).
from untrunc.
That was much mor, than a "bit".
Everything seems more or less clear now.
I'll try to fix some videos on the weekend.
Thank you one more time.
from untrunc.
Related Issues (20)
- recovers only 12% of truncated file HOT 1
- Recovered only 1s of the a 180s video HOT 1
- Assertion `end - begin == length' failed HOT 1
- Two audio streams are being combined into one HOT 11
- Created Recorver file, but that file has no data. HOT 1
- mathops.h:125: Error: operand type mismatch for `shr' HOT 6
- how do I uninstall? I don't see any support on that in the Installation info HOT 1
- No codec found? HOT 1
- Two Tracks Get Combined To Create Distorted Audio HOT 2
- Building on macOS produces error HOT 2
- No codec found!
- Additional macOS steps I had to run HOT 1
- install instructions out of date
- Cannot restore footage with AAC-ELD stream HOT 3
- Latest master fails build HOT 1
- Only a part is being recoverred
- Option to specify path for repaired destination file? HOT 2
- Missing 'Movie Header' atom (mvhd)
- Encounted premature end. when I tick -s, it will quit
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from untrunc.