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Ubuntu

Screencast monitor and speakers using ffmpeg: audio delay problem

Grannik

6/9/23, 12:19 AM

Question? The task is to record simultaneously everything that we see on the monitor and hear from the speakers.

I wrote the following script:

Set the variable:

speaker=alsa_output.pci-[my speakers].analog-stereo.monitor

We write:

ffmpeg -use_wallclock_as_timestamps 1 -f pulse \
-i $speaker -f x11grab -s 1200x900 -r 15 -i :0.0 \
-vcodec qtrle screencast2.mov

The problem is that the sound is recorded with a delay, and of course I need it synchronously. What is the reason? What to fix?

I plowed the entire I> and could not find the answer.

0 + 0

ffmpeg

screen

screencast

mchid

6/9/23, 11:32 AM

Does it have to be for `mov`? Have you tried [using different encoders](https://superuser.com/a/1423215/317065)?

mchid

6/9/23, 12:03 PM

Also, I tried this and I get no audio delay. I am using a USB out for audio so that might make a difference however, it makes it difficult for me to test a solution. However, I did not record for very long. Does the audio start to delay after a certain period of time after you start recording?

mchid

6/9/23, 12:38 PM

Also, when you say there is a delay, do you mean to say that the audio is not in sync with the video (when people move their lips the words do not match) or do you mean to say that the audio does not start recording and there is no audio for the first few seconds of the video (but the words do match when the lips move)?

Grannik

6/9/23, 10:58 PM

when people move their lips the words do not match

mchid

6/10/23, 6:13 AM

Does it help to use different encoders like this? `ffmpeg -use_wallclock_as_timestamps 1 -f pulse -i $speaker -f x11grab -s 1200x900 -r 15 -i :0.0 -acodec aac -vcodec mpeg4 -preset medium -qscale:v 0 rec.mkv`

mchid

6/10/23, 6:16 AM

There's also [this similar answer](https://askubuntu.com/a/154275/167115), however, it is outdated and I **do not recommend using the ppa**. Simply use the ffmpeg command referenced in the question and/or substitute the `-vcodec libx264 -crf 0 -preset ultrafast -acodec pcm_s16le file.mkv` part at the end of your command.

mchid

6/10/23, 6:18 AM

Also, if video quality isn't good, it helps to use `-qscale:v 0`

Grannik

6/13/23, 3:19 PM

mkv? Need to try.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Screencast monitor and speakers using ffmpeg: audio delay problem

TH: จอภาพและลำโพง Screencast โดยใช้ ffmpeg: ปัญหาความล่าช้าของเสียง

RO: Screencast monitor și difuzoare folosind ffmpeg: problemă de întârziere audio

RU: Монитор и динамики скринкаста с использованием ffmpeg: проблема с задержкой звука

VI: Màn hình và loa Screencast sử dụng ffmpeg: vấn đề về độ trễ âm thanh

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