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Avidemux can't seek for key frame

Started by avidemux-fang, May 03, 2021, 07:46:16 AM

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avidemux-fang

hi,

i got a strange problem here. the new avidemux 2.7.8 can't seek the key frame anymore. but if i go back to 2.7.5, it can seek normally again. it's the same mp4 file. what's the possible issue here? can anyone give me some advice? thank you.

ps. i am not a native speaker. so please bear with my english.  :)

eumagga0x2a

Please set the number of lavc decoder threads in Avidemux Preferences --> Multithreading to 2 max.

avidemux-fang

Quote from: eumagga0x2a on May 03, 2021, 07:54:24 AMPlease set the number of lavc decoder threads in Avidemux Preferences --> Multithreading to 2 max.

doesn't help. it still can't seek.
also there's a big difference in newer version. when i added a file, it will pop up a small window shows decoding frame type, and it will process for a while. in 2.7.5 it just open that file and show the first frame. no window or any process.

eumagga0x2a

Quote from: avidemux-fang on May 03, 2021, 08:17:19 AMdoesn't help. it still can't seek.

Have you restarted Avidemux? If yes, please provide that particular file as a sample via WeTransfer (it doesn't need an email address despite the interface trying to suggest otherwise, 2 GiB file size limit), Mega, Dropbox or Google Drive. Obviously, keyframe-based navigation works fine for me with all non-corrupt MP4 samples I have.

Quote from: avidemux-fang on May 03, 2021, 08:17:19 AMalso there's a big difference in newer version. when i added a file, it will pop up a small window shows decoding frame type, and it will process for a while. in 2.7.5 it just open that file and show the first frame. no window or any process.

This is true, prior to 2.7.6, we didn't care to determine frame type (P-frame vs B-frame) in MP4 files. New fixes for the copy mode require exact frame type to be known. If you don't use copy mode, you can skip decoding of slice headers to get the correct frame type by pressing ESC.

avidemux-fang

ok, i have upload a small mp4 file to wetransfer

https://we.tl/t-DGHcUYIXj3

i cut this fragment with version 2.7.5

but in 2.7.8, i can't jump with the key frame or drag with the seek bar.




Quote from: eumagga0x2a on May 03, 2021, 08:50:34 AM
Quote from: avidemux-fang on May 03, 2021, 08:17:19 AMdoesn't help. it still can't seek.

Have you restarted Avidemux? If yes, please provide that particular file as a sample via WeTransfer (it doesn't need an email address despite the interface trying to suggest otherwise, 2 GiB file size limit), Mega, Dropbox or Google Drive. Obviously, keyframe-based navigation works fine for me with all non-corrupt MP4 samples I have.

Quote from: avidemux-fang on May 03, 2021, 08:17:19 AMalso there's a big difference in newer version. when i added a file, it will pop up a small window shows decoding frame type, and it will process for a while. in 2.7.5 it just open that file and show the first frame. no window or any process.

This is true, prior to 2.7.6, we didn't care to determine frame type (P-frame vs B-frame) in MP4 files. New fixes for the copy mode require exact frame type to be known. If you don't use copy mode, you can skip decoding of slice headers to get the correct frame type by pressing ESC.

eumagga0x2a

Thank you for the sample, confirming the issue. My first impression is that the problem is caused by video stream being field-encoded rather than frame-encoded while both fields get marked as keyframe. We probably need to remove/ignore the keyframe flag from the second (or the first?) field in such a keyframe. Looking into it.



eumagga0x2a

Not release, for the next nightly build (MinGW = win64 or VC++ = vsWin64).

If you have a Linux installation too, you can rather easily cross-compile your own win64 build yourself.

avidemux-fang

hi

a quick update here.
i tried the nightly 210510
it works fine. thank you very much.  ;D



Quote from: eumagga0x2a on May 04, 2021, 06:47:12 AMNot release, for the next nightly build (MinGW = win64 or VC++ = vsWin64).

If you have a Linux installation too, you can rather easily cross-compile your own win64 build yourself.