Timeline for FFMPEG Calculate Hash After Encoding Before Writing
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
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| Sep 12, 2016 at 14:50 | vote | accept | Mutant Platypus | ||
| Sep 12, 2016 at 14:40 | comment | added | Mutant Platypus |
And here I was looking up how to split outputs on the Windows command line. (To send the lossless.avi to a file and a pipe. Ugh.) This much better, thanks! The only issue was the output filename in the tee needed to be surrounded in single quotes. Also, I'm not sure that I like SSIM, as it is much more computationally complex than a hash and the output is subject to rounding errors. I'll do a quick performance comparison, but the ideal solution is to just do a bit-for-bit comparison as both streams are flowing through memory... but a hash is close enough.
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| Sep 10, 2016 at 6:42 | comment | added | Gyan | I've edited my first command, so that the AVI output is simultaneously piped to another ffmpeg instance which then computes hashes on the decoded frames. | |
| Sep 10, 2016 at 6:41 | history | edited | Gyan | CC BY-SA 3.0 |
altered first command so that a 2nd instance runs in parallel computing the hashes of the decoded frames.
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| Sep 9, 2016 at 20:16 | comment | added | Gyan | No. Encoding occurs after decoding (and filtering), so that provision isn't there. Looks like you are concerned about disk I/O. What you could do is pipe lossless avi to another ffmpeg instance which computes hashes. | |
| Sep 9, 2016 at 20:01 | comment | added | Mutant Platypus | Is there no way to take encoded packets and fork them to a muxer and a decoder in the same FFMPEG instance? | |
| Sep 9, 2016 at 19:37 | comment | added | Mutant Platypus |
This answer made so many different things click for me (hash doesn't use raw input, -map 0 instead of split, and that's what a tee is for). Thanks! But it doesn't avoid the problem of reading lossless.avi off of the disk to decode/compare it. In fact, you are also reading the original images off of the disk twice to compare them to the decoded image.
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| Sep 9, 2016 at 18:00 | history | edited | Gyan | CC BY-SA 3.0 |
deleted 68 characters in body
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| Sep 9, 2016 at 17:52 | history | answered | Gyan | CC BY-SA 3.0 |