[FFmpeg-user] encoding video from png diffs

[Joshua Grauman]

Sorry for another question, but I'm having a hard time figuring out why 
this doesn't work. I've written a program to output raw image data 
(32-bit rgba), frame after frame. I'm trying a test to encode it to mp4, 
but this command says:

./shm | ffmpeg -f image2 -r 30 -s 1274x541 -pix_fmt rgb32 -vcodec rawvideo -i - out.mp4

Could find no file with path 'pipe:' and index in the range 0-4
pipe:: No such file or directory

What am I doing wrong?

Thanks!

Josh


On Fri, 2 Sep 2016, Joshua Grauman wrote:

> I've been looking for a way to screencast an app with alpha, but I haven't 
> found one yet (but if someone knows of one, I'd love it). So I'm working on 
> modifying my app to generate png's at 30 frames per second.
>
> Josh
>
>>  2016-09-02 7:29 GMT+02:00 Joshua Grauman <jnfo at grauman.com>:
>> >  I have another different, but related question. What format would you
>> >  suggest for storing my screencast in? The resulting video is going to be
>> >  1080p30 and it needs to have an alpha channel
>>
>>  Which screencast technology allows to record an alpha channel?
>>  mpng should be best for screencasts, some people like utvideo.
>>
>>  Carl Eugen
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