From 9aeeeb63f7e1ab7b0b7bb839a5f258667a2d2d78 Mon Sep 17 00:00:00 2001 From: Fabrice Bellard Date: Wed, 20 Dec 2000 00:02:47 +0000 Subject: Initial revision Originally committed as revision 2 to svn://svn.ffmpeg.org/ffmpeg/trunk --- doc/ffmpeg.txt | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 doc/ffmpeg.txt (limited to 'doc/ffmpeg.txt') diff --git a/doc/ffmpeg.txt b/doc/ffmpeg.txt new file mode 100644 index 0000000000..b7fffcdd29 --- /dev/null +++ b/doc/ffmpeg.txt @@ -0,0 +1,62 @@ +* ffmpeg can use YUV files as input : + + ffmpeg /tmp/out.mpg /tmp/test + +If will use the files: +/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V, +/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc... + +The Y files use twice the resolution of the U and V files. They are +raw files, without header. They can be generated by all decent video +decoders. + +* ffmpeg can use a video4linux compatible video source : + + ffmpeg /tmp/out.mpg + + Note that you must activate the right video source and channel + before launching ffmpeg. You can use any TV viewer such as xawtv by + Gerd Knorr which I find very good. + +* There are some importants options to know: + +-s size set frame size [160x128] +-f format set encoding format [mpeg1] +-r fps set frame rate [25] +-b bitrate set the bitrate in kbit/s [100] +-t time set recording time in seconds [10.0] + +The frame size can also be: cif, qcif, sqcif and 4cif. +The encoding format can be mpeg1, h263 or rv10. + +Advanced options are: + +-d device set video4linux device name +-g gop_size set the group of picture size. + An 'intra' frame is generated every gop_size frames. +-i use only intra images (speed up compression, but lower quality). +-c comment set the comment string. + +Comment strings are only used for Real Video(tm) encoding. Tags are +used in the comment string. A typical comment string is: + +"+title=Test Video +author=FFMpeg +copyright=Free +comment=Generated by FFMpeg 1.0" + +The output file can be "-" to output to a pipe. This is only possible +with mpeg1 and h263 formats. + +* Tips: + +- For low bit rate application, use a low frame rate and a small gop + size. This is especially true for real video where the Linux player + does not seem to be very fast, so it can miss frames. An example is: + + ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm + +- The parameter 'q' which is displayed while encoding is the current + quantizer. The value of 1 indicates that a very good quality could + be achieved. The value of 31 indicates the worst quality. If q=31 + too often, it means that the encoder cannot compress enough to meet + your bit rate. You must either increase the bit rate, decrease the + frame rate or decrease the frame size. + -- cgit v1.2.3