Re: [PLUG] Transcoding MTS vids to something else for frame extraction

[Rich Freeman via plug <plug@lists.phillylinux.org>]

On Mon, Aug 31, 2020 at 8:12 PM JP Vossen via plug
<plug@lists.phillylinux.org> wrote:
>
> If I'd thought about it, I should have checked to see if the camera had
> a "raw" mode, which it probably does.  That would have been good to
> shoot this in, assuming the memory card was big enough.

Cheaper cameras may or may not provide the ability to record raw
stills, and almost never have the ability to record raw video.  If
anything they'll probably record raw stills at a slower rate than jpgs
since there is more data to be written to the memory card, which tends
to be the bottleneck.  While jpegs require more processing it is
basically a data reduction optimization - the processor is optimized
for compressing jpgs so the raw image can quickly be compressed and
then the original is discarded, which greatly reduces the memory
demand on the buffer.  Additionally with less to be written per-frame
the buffer is emptied much faster.

On higher-end cameras it is pretty common for a camera to only support
a dozen or so raw images in the buffer before having to reduce the
frame rate, but they could support dozens or even hundreds of jpegs.
A raw image is usually 10-20x larger than a jpeg of comparable visual
quality at first glance.

For video the consumption of raw frames is even more significant,
since you're losing both intra- and inter-frame compression.  Raw 8bit
1080p24 video is 400Mbps, while broadcast 1080p TV tends to be
10-20Mbps tops, and more bandwidth-constrained stuff is more like
5-10Mbps.  Bitrates get even higher if you increase the resolution or
bit depth and better cameras do both.  Note that even UHS-I at its
baseline only does 400Mbps, though you can get cards that do double
that, and there are faster standards.

-- 
Rich
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