[FFmpeg-user] Faster codec with alpha

[Joshua Grauman]

I'll keep that in mind if I really need extra speed. Thanks!

Josh

On Fri, 2 Dec 2016, Fred Perie wrote:

> 2016-12-02 17:38 GMT+01:00 Joshua Grauman <jnfo at grauman.com>:
>>
>> Thanks guys, I'll look into these ideas!
>>
>> Josh
>>
>>
>> On Fri, 2 Dec 2016, Paul B Mahol wrote:
>>
>>> On 12/2/16, Joshua Grauman <jnfo at grauman.com> wrote:
>>>>
>>>> Hello all,
>>>>
>>>> I am using the following command successfully to generate a screencast.
>>>> The video comes from my program 'gen-vid' which outputs the raw frames
>>>> with alpha channel. The resulting .avi has alpha channel as well which
> is
>>>> my goal. It all works great except that my computer can't handle doing
> it
>>>> real-time. So I am wondering if there is a different vcodec I could use
> to
>>>> achieve the same result that was less demaning on the cpu? I am willing
> to
>>>> sacrifice some compression for more speed, but would prefer not to have
> to
>>>> store all the raw frames without any compression. Storing the alpha
>>>> channel is also a must. It is preferable if the compression is lossless.
>>>> Does anyone have any other suggestions for compression other than png
> that
>>>> may be faster? Thanks!
>>>
>>>
>>> utvideo, huffyuv, ffvhuff
>>>
>>>>
>>>> ./gen-vid | ffmpeg -f rawvideo -pixel_format bgra -video_size 1920x1080
>>>> -framerate 30 -i - -vcodec png over.avi
>>>>
>>>> Josh
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>>>
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>>
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>
> Hi Joshua
> I regularly use ffv1 with pix_fmt bgra
> If speed is really a problem when reading/decoding, you can  also consider
> having two files one containing the alpha channel codec ffv1 pix_fmt gray8
> and the color using a codec like H264
> I don't know how to do this with the ffmpeg command. I use the ffmpeg
> libraries and a specific program.
>
> Fred
>
>
>
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