[FFmpeg-user] Mix a video with an audio file
Paul B Mahol
onemda at gmail.com
Sun Jan 19 22:56:27 EET 2020
On 1/19/20, Michael Koch <astroelectronic at t-online.de> wrote:
> Am 19.01.2020 um 21:01 schrieb Paul B Mahol:
>> On 1/19/20, Michael Koch <astroelectronic at t-online.de> wrote:
>>> I've just found a problem that can be reproduced as follows:
>>> Step 1: Make a 6 seconds test video with 1kHz tone. The file is ok when
>>> ffmpeg -f lavfi -i testsrc2=size=vga -f lavfi -i sine=1000 -t 6 -y
>>> Step 2: Make a 10 seconds audio file with silence and a short 3kHz tone
>>> at t=3s. The file is ok when played.
>>> ffmpeg -f lavfi -i "sine=3000:duration=0.1" -af adelay=3000,apad -t 10
>>> -y audio.wav
>>> Step 3: Combine both files into one video, and the audio sources shall
>>> be mixed:
>>> ffmpeg -i video.mp4 -i audio.wav -filter_complex
>>> "[0:a][1:a]amix=weights='1.0 1.0'" -shortest -y out.mp4
>>> The output video has the correct length 6s, but I don't understand why
>>> the 1kHz tone disappears after 4s and the last 2s are silence.
>>> The console output is below.
>> Can not reproduce using nut container.
> When I change the output filename to out.nut, then it works as expected
> (but with terrible image quality). Why doesn't it work with mp4 output?
Use different video encoder. Who knows?
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