[FFmpeg-user] low quality video using raspberry pi

shuvro majumder shuvromaj at gmail.com
Sun Feb 21 14:10:41 CET 2016

thanks for replying. I tried to use -qscale 2 -mbd 2. But the size of the
video is now much greater than before. I have to capture very low quality
video. <150MB/hour. And also, -r 20 -s 320*240 is working,but it is
capturing 10fps video after sometimes,but its property is 20fps, so video
is faster when I am playing that.

And when I use -b, it said:

Please use -b:a or -b:v, -b is ambiguous

so I used -b:v 100k, now its recording video, but it is telling:

frame=    1 fps=0.5 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A
speed=   0x

you can see, I am getting no video. How I should use bitrate?
Another thing, every time I am capturing video, it is telling,

[mpeg @ 0x1adda40] VBV buffer size not set, using default size of 130KB
If you want the mpeg file to be compliant to some specification
Like DVD, VCD or others, make sure you set the correct buffer size

How to set buffer size?

On Sun, Feb 21, 2016 at 6:13 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> shuvro majumder <shuvromaj <at> gmail.com> writes:
> > ffmpeg -f video4linux2 -s 320*240 -r 20 -i /dev/video0 out.mpg
> (-r 20 may be wrong, -s 320x240 looks wrong.)
> If this is meant as a fast intermediate step to loose as
> little quality as possible, use -qscale 2 -mbd 2
> If this has size constraints, please add -b with an
> appropriate bitrate for your size constraints.
> > ffmpeg -i out.mpg -c:v libx264 -preset slower -crf 30 -c:a copy
> output.h264
> If you have size constraints (you wrote that you have them)
> do not use a constant quality but specify a bitrate.
> Note that the -h264 file format that you specified does
> not support audio, so -acodec copy makes no sense.
> Carl Eugen
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> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
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