I've got some existing code using a SequenceGrabber to write a video/
audio movie, using a custom VDIG. This all works fine.
I'm in the process of using ICM compression/decompression so that I
can enable the output of non-keyframes in H264, using ideas and
concepts from the CaptureAndCompressIPBMovie code along with
additions from Brad Ford (AAC audio) last year.
This all works, but it seems slower than the existing sequence
grabber code. For testing, Im not using H264 - I'm using the Apple
Intermediate Codec. When capturing full screen on a macbook pro,
using the original non-ICM code I'm getting something in the order of
15fps (that includes capture, compression and writing to disk).
When using the ICM code, it's down to about 10fps.
My questions are these:
1) Would I improve performance using AddSampleTableToMedia, if I
buffer compressed frames and don't add them to the movie one by one?
2) Is there any point me putting the write code onto a separate
thread, so that I can return control to QT as soon as possible?
I'm quite aware that I've not posted code. This is intentional as I
want to focus on the broad picture at the moment - as in, I'm
interested if threading and internal buffering is worth the work
before I go down that route, or if I'm thinking about this the wrong
way.
I'd like to take the time to also thank all those (Apple and others)
who have taken the time to answer questions. I spent quite some
time today looking through old emails in an attempt to get AAC audio
compression going (it was in the end trivial to get working), and I
noticed some of my old posts. Reading them, I felt for those who
had to answer them (gaaaa!). So I wanted to thank you for putting
up with me :-)
I sincerely hope this email makes more sense that some of my
previous 'communications'!
Regards,
Neil Clayton
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