[FFmpeg-user] ffmpeg to get yuv file

[Wu, Mandy]

Hi, All,
What is difference of decoding mp4 to yuv and decoding the demuxed H.264 file to yuv?
I want to get yuv file of a source video (mp4). I tried below 2 commands:
Decode to yuv file directly from mp4: 
	ffmpeg -i souce.mp4 source1.yuv
Demux the source file, and Decode the .H264 file to yuv:
	ffmpeg -i source.mp4 -vcodec copy -an source.h264
	ffmpeg -i source.h264 source2.yuv
I found size of the 2 yuv files is different. previous source1.yuv is bigger than the second one.
Which one is correct? And which one should I use for psnr calculation? Thanks!


Thanks,
Mandy