ffmpeg pipe to mpeg2enc

Occasionally, I'll need to send a video stream into mpeg2enc. Mpeg2enc doesn't take an input file; it only accepts a yuv4mpeg stream. In order to send a yuv4mpeg stream to mpeg2enc, I do this using ffmpeg and the -f yuv4mpegpipe command line switch. Also, for best quality, I will send the stream using the FFMPEG variant of the Huffyuv lossless compression algorithm. ffyhuff is an enhanced version of Huffyuv that compresses better than Huffyuv.

Update 2009/05/19As per Dan Dennedy's comment below, ffmpeg's yuv4mpegpipe command will ignore the -vcodec option and pipe the video stream to mpeg2enc using an uncompressed C420jpeg stream, which is an uncompressed YUV format. Certainly good enough for the likes of me!
*** end update ***

Here is a sample command to reencode a 720P video stream as a yuv4mpeg pipe to mpeg2enc:
ffmpeg -threads 4 -i INPUT.M2V -f yuv4mpegpipe - ¦ mpeg2enc --verbose 0 --multi-thread 4 --aspect 3 --format 3 --frame-rate 4 --video-bitrate 18300 --nonvideo-bitrate 384 --interlace-mode 0 --force-b-b-p --video-buffer 448 --video-norm n --keep-hf --no-constraints --sequence-header-every-gop --min-gop-size 6 --max-gop-size 6 -o OUTPUT.M2V

Note that I am taking advantage of the eight processors in my dual quad core using the multithread switches in the commands to both ffmpeg and mpeg2enc. Note that the eight threads have been split evenly, four to each encoder, to avoid CPU context switching. (Thanks again, Dan!)

Here's another trick: to see the header information of a YUV4MPEG stream, pipe the FFmpeg conversion stream to head -1 like so:
ffmpeg -i intermediate.mov -vcodec mpeg2video -f yuv4mpegpipe - | head -1
ffmpeg -i intermediate.mov -pix_fmt yuv420p -f yuv4mpegpipe - | head -1

The FFmpeg output should show you some very important information, bolded below:
the output format: YUV4MPEG2 stream
height and width: 1280x720
framerate: 30001:1001 (or 29.97fps)
colorspace: C420JPEG
not sure what IP: 1 or XYSCSS is

Duration: 01:19:46.74, start: 0.000000, bitrate: 110301 kb/s
Stream #0.0(eng): Video: mjpeg, yuvj420p, 1280x720 [PAR 1:1 DAR 16:9], 108762 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc
Stream #0.1(eng): Audio: pcm_s16be, 48000 Hz, 2 channels, s16, 1536 kb/s
Output #0, yuv4mpegpipe, to 'pipe:':
Metadata:
encoder : Lavf52.64.2
Stream #0.0(eng): Video: mpeg2video, yuv420p, 1280x720 [PAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 90k tbn, 29.97 tbc
Stream mapping:
Stream #0.0 -> #0.0
Press [q] to stop encoding
YUV4MPEG2 W1280 H720 F30000:1001 Ip A1:1 C420jpeg XYSCSS=420JPEG
Sweet, eh?

As a final note, I am a bit confused on the differences between FFMPEG compression algorithms: ffyhuff and ffv1. If someone has pointers to the documentation on these, I'd be interested in finding out more. A google search just added to my confusion.

the mule

References
mpeg2enc man page
mpeg2enc manual
ffmpeg vs mpeg2enc
Huffyuv
FFV1
FFMPEG How To

related posts
http://crazedmuleproductions.blogspot.com/2010/01/batch-render-redux.html
/2010/01/compile-times-performance-improved.html
FFMPEG HowTo