ffmpeg and alsa/pulseaudio

ffmpeg and alsa/pulseaudio

[Ekaitz Zarraga]

Hi,

I'm trying to make a screencast with ffmpeg and I'm having issues.

I had a screen recording script on the past, based on alsa, but it's not working in guix because it looks like ffmpeg wasn't compiled with alsa. Is that true? Is there something I missing to activate alsa on ffmpeg?


This is the command I was running:

ffmpeg \
    -y -f x11grab -draw_mouse 1 -framerate 25 -video_size 1920x1080 -i $DISPLAY \
    -f alsa -ac 2 -i default \
    -pix_fmt yuv420p -c:v libx264 -preset veryfast \
    -c:a libmp3lame -q:v 1 -s 1920x1080 -f matroska \
    output.mkv




I tried to make it with pulseaudio replacing alsa by pulse in the command but the audio is distorted. It sounds very fast.

Any idea? Do you use ffmpeg for screen recording too?

Thanks

Re: ffmpeg and alsa/pulseaudio

[Leo Famulari]

On Tue, Apr 07, 2020 at 11:54:35AM +0000, Ekaitz Zarraga wrote:
> Hi,
> 
> I'm trying to make a screencast with ffmpeg and I'm having issues.
> 
> I had a screen recording script on the past, based on alsa, but it's not working in guix because it looks like ffmpeg wasn't compiled with alsa. Is that true? Is there something I missing to activate alsa on ffmpeg?
> 
> 
> This is the command I was running:
> 
> ffmpeg \
>     -y -f x11grab -draw_mouse 1 -framerate 25 -video_size 1920x1080 -i $DISPLAY \
>     -f alsa -ac 2 -i default \
>     -pix_fmt yuv420p -c:v libx264 -preset veryfast \
>     -c:a libmp3lame -q:v 1 -s 1920x1080 -f matroska \
>     output.mkv

I tried this but it failed with ":0: Invalid argument". That's the
$DISPLAY variable. Do you know what it should say?

Re: ffmpeg and alsa/pulseaudio

[Ekaitz Zarraga]

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, May 29, 2020 3:34 AM, Leo Famulari <leo@famulari.name> wrote:

> On Tue, Apr 07, 2020 at 11:54:35AM +0000, Ekaitz Zarraga wrote:
>
> > Hi,
> > I'm trying to make a screencast with ffmpeg and I'm having issues.
> > I had a screen recording script on the past, based on alsa, but it's not working in guix because it looks like ffmpeg wasn't compiled with alsa. Is that true? Is there something I missing to activate alsa on ffmpeg?
> > This is the command I was running:
> > ffmpeg \
> > -y -f x11grab -draw_mouse 1 -framerate 25 -video_size 1920x1080 -i $DISPLAY \
> > -f alsa -ac 2 -i default \
> > -pix_fmt yuv420p -c:v libx264 -preset veryfast \
> > -c:a libmp3lame -q:v 1 -s 1920x1080 -f matroska \
> > output.mkv
>
> I tried this but it failed with ":0: Invalid argument". That's the
> $DISPLAY variable. Do you know what it should say?

Hi Leo,

Thanks for the answer. I have :1 in DISPLAY and it's not failing because of that.

More on the issue: I had to use a different microphone for this just because of this issue. Looks like when I use a USB microphone and use pulseaudio engine it breaks somehow and records audio with wrong timestamps. An analog microphone works well.
With alsa I found a working configuration but it doesn't work :(

Thanks!