[FFmpeg-devel] Custom Video Encoding and Decoding

[Paul B Mahol]

On 7/29/20, Jaeho Bang <jaeho.bang at gmail.com> wrote:
> Dear members of ffmpeg-devel,
>
> I am currently working on a research project and from looking over the
> examples and documentation in the ffmpeg repository, I believe I need to
> implement a custom encoder / decoder to perform my task.
>
> To first explain the project idea, currently I am working mainly with
> surveillance footages. Using a traditional video decoder, I convert the
> video into series of image frames and perform clustering to create frame
> groups. Then using some performance metric, my algorithm selects a
> representative frame from each group. By implementing a custom encoder and
> decoder, I aim to improve the speed of extracting these representative
> frames.
>
> To further explain, I would like the custom encoder to be able to force the
> frames I have chosen (representative frames) to be i-frames. The assumption
> is that when analyzing videos, we only need to evaluate these
> representative frames instead of the whole video (this I have already
> experimentally confirmed), and extracting i-frames is faster than
> extracting a combination of i-frames, b-frames, and p-frames.
>
> Also, I would like to implement a decoder to quickly extract the series of
> frames I give as input (they will all be i-frames). Through preliminary
> experiments, I realized that extracting only i-frames by using the command
> 'select pict_type\I' query command only gives a 2x speed boost compared to
> extracting all frames within the video. Hopefully, by implementing a custom
> decoder, I aim to further increase this extraction speed.
>
> Is there any code I can refer to? Is my assumption of 'if I were to
> implement a custom decoder, the extraction speed would be faster than using
> the keyword select to get all the i frames' valid?
>
> Any help would be greatly appreciated. Thank you and have a wonderful day.
>

Sorry, but with all due respect, the need for custom decoder does not
make any sense.

> Sincerely,
> Jaeho Bang
>
> --
> *Jaeho Bang*
> *PhD Student in Computer Science*
> Georgia Institute of Technology
> North Ave NW, Atlanta, GA 30332, USA
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