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ffmpeg with h264_videotoolbox cannot encode a video properly #304
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I tried, and I cannot reproduce the issue (either with my own install of with a TestFlight install). Which means it's either related to a bug that happens after several runs of ffmpeg (which will be hard to debug) or to differences in system installs (which will be hard to debug). These "Invalid DTS" were frequent when I was running the master version of ffmpeg, I haven't seen it since I compiled version 4.4. |
Thanks for replying. Umm, it's weird. Maybe it's because of iPadOS 15. I will try on iOS 14.7.1 or iPadOS 14.7.1 later.
This is probably not the cause. In my environment, the issue happens even after all a-Shell windows are closed and a-Shell is force-quitted.
I'll try in another device. |
My tests were on iPadOS 15 too. The mystery gets weirder. |
Are you also using Developer Beta 7? |
Thanks. So it looks like a random issue, affecting some devices running iOS 15 developer beta 7, but not all of them. That's going to be tough to debug... |
h264_videotoolbox is a hardware encoder, so the issue might depend on a hardware. What's your device? |
I tested two more other devices. 11-inch iPad Pro 3rd generation running iPadOS 14.7.1Result: The issue was not reproduced. 11-inch iPad Pro 2nd generation running iPadOS 15 Developer Beta 7 (19A5337a)Result: The issue was reproduced. Current summaryIn my case, I can reproduce the issue on all my iOS/iPadOS 15 devices. So, I want to know what device @holzschu tested on. Reproduced:
Not reproduced:
|
I added two test results. I found that iPad Air 2 cannot reproduce the issue even if running iPadOS 15 Developer Beta 7. I tried reinstalling a-Shell, but the result was the same. So I guess it depends on the hardware whether it reproduces or not. Reproduced:
Not reproduced:
|
Thank you for all these tests, and for including the processors. My hope is that it will get better once a-Shell (and ffmpeg) are compiled with Xcode 13 GM (once it is available). For now, all the builds are compiled with Xcode 12.5. |
I don't know why, but it seems that this issue has been resolved in iPadOS 15.2 Beta 2 on my 12.9-inch iPad Pro 5th generation. |
Good news! As a result of some experiments, at least iOS 15.0.2 or earlier has this issue, but it has been fixed in iOS 15.1. |
When I run the command like the following, the playback time of
out.mov
becomes very long.In this case, the playback time of
Big_Buck_Bunny_1080_10s_5MB.mp4
is 00:00:10.00, however, the one ofout.mov
is 92:17:02.23 as you can see from the following results. if you test in your own environment, you can download the input video here.I think that the warning messages like
[mov @ 0x10905c400] Invalid DTS: 34132480 PTS: 17066496 in output stream 0:0, replacing by guess
might relate to the issue because they didn't appear in the macOS version.Those warning messages didn't appear in the macOS version of ffmpeg, and the playback time of
out.mov
is also normal.The macOS version of ffmpeg I used was installed from Homebrew. The differences between the two are as follows.
a-Shell 1.7.5 (185) (TestFlight) (12.9-inch iPad Pro 5th generation running iPadOS 15 Developer Beta 7 (19A5337a)):
macOS:
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