yawnmoth
10th November 2002, 06:08
If I-frames are just still pictures, and it's the p and b frames that make something a video codec, it seems reasonable that they'd use some existing format for still pictures, like JPEG, or something... do they? or do they instead use some sort of format that only came about in the specification for the video as well?
and if the later is the case... if the format for i-frames achieved better compression than formats like JPEG, then it seems like there ought to be some sort of iframe format for still pictures released, and vice versa. Also, if it were a format like JPEG... shouldn't MPEG encoders have more options, then?
I mean, with the JPEG encoder in Photoshop 7, you can set the quality, and say whether or not it's format is baseline, baseline optimized, or progressive (and how many scans)... it seems to me like if dedicated JPEG encoders had them, and MPEG1/2/4 used JPEG for the iframes, that MPEG1/2/4 encoders could benefit from options like these...
and if the later is the case... if the format for i-frames achieved better compression than formats like JPEG, then it seems like there ought to be some sort of iframe format for still pictures released, and vice versa. Also, if it were a format like JPEG... shouldn't MPEG encoders have more options, then?
I mean, with the JPEG encoder in Photoshop 7, you can set the quality, and say whether or not it's format is baseline, baseline optimized, or progressive (and how many scans)... it seems to me like if dedicated JPEG encoders had them, and MPEG1/2/4 used JPEG for the iframes, that MPEG1/2/4 encoders could benefit from options like these...