Doom9's Forum - View Single Post - Quicktime Import Filter - Test Version, Still Buggy - 2006-01-09

tateu · 19th December 2005, 21:19

Bond,
I can't seem to get it to output YV12 but I'm still trying. The Quicktime developer site has sample code to use for determining if a given codec can output to the desired format (it uses a codec's cpix resource). The code doesn't seem to work with 3rd party codecs but for the one's I've gotten it work on, kYUV420PixelFormat always returns false. kYUVSPixelFormat, k24BGRPixelFormat and k32BGRAPixelFormat return true.

For QTInput, there are really only two quality options: equal to 0 and greater than 0. Quality = 0 sets the decoder in a normal (lower quality) decoding mode, probably meant for a preview mode so you get a faster decode. It does not have an affect for all codecs but for some of them, DV25 for example, there is a large drop in quality when set to 0 (very blurry output). I have not tried it on an x264 file yet but if you leave it set at the default value of 100 you should get the best possible quality.

For QTOutput, quality sets the basic encoder compression parameters. If you open any program that can export to Quicktime you get a dialog box where you choose the codec, fps, depth and quality (least, low, medium, high, best). This quality setting is what gets set by the QTOutput quality param. This does not affect all codecs, but for mjpa this adjusts the amount of jpeg compression per frame. For an mjpa test encode I tried:
quality = 0, resulted in a data rate of 11.55 mbit/s
quality = 20, resulted in a data rate of 15.00 mbit/s
quality = 40, resulted in a data rate of 29.14 mbit/s
quality = 60, resulted in a data rate of 46.48 mbit/s
quality = 80, resulted in a data rate of 63.45 mbit/s
quality = 100, resulted in a data rate of 105.11 mbit/s

There are also sometimes more advanced compression options (data rate, interlaced, etc.). These are not yet available with my filter.

I haven't done any speed tests. Are you looking for speed compared to mencoder/ffmpeg quicktime decoding or to compared to avi vfw decoding?

peter100m,
That's good news. I'm still going to try and have an option to return raw data. This will also facilitate a planned direct stream copy mode from quicktime to avi.

19th December 2005, 21:19	#6 \| Link
tateu Registered User Join Date: Jan 2002 Location: Los Angeles, CA USA Posts: 132	Bond, I can't seem to get it to output YV12 but I'm still trying. The Quicktime developer site has sample code to use for determining if a given codec can output to the desired format (it uses a codec's cpix resource). The code doesn't seem to work with 3rd party codecs but for the one's I've gotten it work on, kYUV420PixelFormat always returns false. kYUVSPixelFormat, k24BGRPixelFormat and k32BGRAPixelFormat return true. For QTInput, there are really only two quality options: equal to 0 and greater than 0. Quality = 0 sets the decoder in a normal (lower quality) decoding mode, probably meant for a preview mode so you get a faster decode. It does not have an affect for all codecs but for some of them, DV25 for example, there is a large drop in quality when set to 0 (very blurry output). I have not tried it on an x264 file yet but if you leave it set at the default value of 100 you should get the best possible quality. For QTOutput, quality sets the basic encoder compression parameters. If you open any program that can export to Quicktime you get a dialog box where you choose the codec, fps, depth and quality (least, low, medium, high, best). This quality setting is what gets set by the QTOutput quality param. This does not affect all codecs, but for mjpa this adjusts the amount of jpeg compression per frame. For an mjpa test encode I tried: quality = 0, resulted in a data rate of 11.55 mbit/s quality = 20, resulted in a data rate of 15.00 mbit/s quality = 40, resulted in a data rate of 29.14 mbit/s quality = 60, resulted in a data rate of 46.48 mbit/s quality = 80, resulted in a data rate of 63.45 mbit/s quality = 100, resulted in a data rate of 105.11 mbit/s There are also sometimes more advanced compression options (data rate, interlaced, etc.). These are not yet available with my filter. I haven't done any speed tests. Are you looking for speed compared to mencoder/ffmpeg quicktime decoding or to compared to avi vfw decoding? peter100m, That's good news. I'm still going to try and have an option to return raw data. This will also facilitate a planned direct stream copy mode from quicktime to avi.