[Ssc-dev] New Example

[Andrew Senior]

This is great. FFMPEG seems like a good way forward.
I've not followed the argument fully. With ffmpeg there's no need to use MOV
container or MJPEG compression is there? I didn't follow the code too
closely, but I think you're saving the preview frames as JPEGs then
compressing them to an mjpeg with ffmpeg. In this scenario does FFMPEG
reencode the jpegs, or just embed them in the container stream? The latter
presumably means the video is constructed with negligible CPU- the CPU is
all in the decompression / recompression of the original frames at recording
time.

With ffmpeg we could transcode a recorded video (full native format &
framerate) and make our own
filter (http://wiki.multimedia.cx/index.php?title=FFmpeg_filter_HOWTO) that
does the redaction based on a second file that stores the redaction regions.
It could also dump the redacted information to a separate stream, and with
ffmpeg we might be able to embed this, encrypted into the container.

Redacting a video after recording has the advantage of allowing the same
workflow that we have in the current release - you can redact previously -
recorded content.

Andrew


On Fri, Jul 29, 2011 at 12:29 AM, Nathan of Guardian <
nathan at guardianproject.info> wrote:

> On 07/28/2011 11:58 PM, Shawn Van Every wrote:
> > Runtime exec for now.  NDK/JNI down the road.
>
> Runtime is fine with me! That is what we do for Orbot
> .
> >> What are the settins you are using at this point?
> > I think the problem has to do with the YUV/JPEG/JPEG/MP4 compression
> chain.  We'll have to skip some of these steps..
>
> It would be great to get a sense of "maximum possible quality" vs
> "estimated time for processing each frame".
>
> > Some issues:
> > 1: I reinstall ffmpeg every time
>
> Yes, that should be fixed.
>
> > 2: It is way big (>20MB)
>
> Eh. Not so bad.
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