To clarify: My goal is not to build a full video player that could stream
infinite amounts of frames perfectly, with sound, and supporting the full range
of movie formats. We are not trying to replace or replicate VLC or rv.
We just want to extend iv to support a flipbook feature that could cycle
through as many frames as we can fit in memory, at 24 or 30 fps, with the
obvious UI controls (play, stop, forward or back a frame, timeline/scrubber,
etc), no sound, no direct support of movie formats. I'm ok with stuttering or
delays in cases where there are too many frames to even fit in CPU RAM. This
project probably requires double (or more) buffering on the GPU, perhaps a
separate thread to decode/read-ahead, but not an elaborate redesign of the app.
That's more than enough challenge for a summer project, and likely to be very
useful to iv users. But as I said, we are not trying to be rv.
-- lg
On Mar 23, 2012, at 10:23 AM, Ciaran Wills wrote:
>
> On Mar 23, 2012, at 1:03 AM, Larry Gritz wrote:
>
>> Hey, how does that work? Has anybody here written a good playback app
>> before? (I haven't.) The one I use at work, for example, seems to be able
>> to play back essentially infinite amounts of video (I've certainly made it
>> play tens of seconds, maybe minutes), and it doesn't appear to be showing me
>> a lossy of lower precision image than when I view the stills, nor do I ever
>> notice it pausing to refill a buffer (other than when it first starts up).
>> So do apps like this work, particularly when the full image stack would
>> exceed RAM?
>
> I've written one (Although I'm not sure I'd go as far as calling it 'good')
> and it is hard. The trick is to try to keep data streaming from disk to
> memory, decompressing and from memory to the gpu as fast as the hardware will
> let you and all at the same time - so think threads, careful caching/memory
> management and a certain amount of operating system and video driver voodoo.
> Dealing with different GPUs with different capabilities just makes it harder
> still. That's why we're more than happy to pay for RV rather than write
> another one ;)
>
>> Anyway, doing this well is certainly a good sized summer project, don't fool
>> yourself into thinking it's going to be a simple modification of the current
>> timer and adding a couple buttons.
>
> I definitely agree with Daniel - we should limit the initial scope of this
> project to being a in-memory flipbook, and add to it if we get that far (hey,
> did someone say quicktime support?)
>
--
Larry Gritz
[email protected]
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