I have an algorithm that generates a video frame by frame, which I am refactoring to stream the images to ffmpeg rather than save them all to disk first.
The algorithm currently generates and saves a bunch of QImages then executes ffmpeg (with QProcess). The new version will generate QImages then stream them out to ffmpeg's stdin via QProcess. I can do all that just fine.
The issue is, I'm not actually generating the images serially, I'm generating them on a thread pool, maybe 12-16 at a time (just using QtConcurrent). I'd like to keep this parallelism for performance reasons, since the operation (even excluding image encoding and file I/O) does take a long time.
So my question is, does ffmpeg have something like image2pipe but that can take the images slightly out of order (let's assume there's some sane maximum offset, +/- 20 or so)?
If not, my solution will be to divide the image set into small batches, then for each batch, run it on the pool, reorder it, and stream them in the correct order; sacrificing some fraction of performance depending on the batch size. I'd rather not do that just because the code right now is dirt simple, and simple is good. So I'm wondering if there's a way to get ffmpeg to accept the images out of order.
They're at a fixed frame rate, if that is useful (maybe there's some way to set PTS's or something, then I just find a codec + container that can store out-of-order frames).
