Re: Video capture issues

Subject: Re: Video capture issues

From: Brad Ford <email@hidden>

Date: Mon, 9 Jul 2007 10:31:50 -0700

Delivered-to: email@hidden

<SNIP>

The code that I am using to configure the sequence grabber is below, and compiles without warning.

-(void)configureSequenceGrabber
{
grabber = OpenDefaultComponent(SeqGrabComponentType,0);

SGInitialize(grabber);

SGSetDataRef(grabber,0,0,seqGrabDontMakeMovie);

SGNewChannel(grabber,VideoMediaType,&videoChannel);
SGNewChannel(grabber,SGAudioMediaType,&audioChannel);

SGSetChannelUsage(videoChannel,seqGrabRecord);
SGSetChannelUsage(audioChannel,seqGrabRecord);

SGSetDataProc(grabber,&GrabberDataProc, (long)self);

SGStartRecord(grabber);

[self taskGrabber];

First problem - you're not checking for errors. You don't know what's succeeding and failing.

Second thing - does -taskGrabber just call SGIdle? You're not ever going to get anything out of Sequence Grabber if you don't give it regular idle time (like 30-60 idles per second). You need to kick off a timer in which you call SGIdle, otherwise your data proc will never be called, because all the source video/audio is being dropped.

-Brad Ford

QuickTime Engineering

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References:

>Video capture issues (From: Adam Chester <email@hidden>)