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Message: 5 Date: Wed, 7 Dec 2005 10:25:59 +0000 From: Amadeus Stevenson <amadeus.stevenson at gmail.com> Subject: [Ffmpeg-user] Is ffmpeg mpeg2video "industry standard"? To: FFMpeg user questions and RTFMs <ffmpeg-user at mplayerhq.hu> Message-ID: <1c42f0e0512070225q45b7a7e3s3d63ec9409575233 at mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1

Hi all,

I'm using ffmpeg to create mpeg2 videos from mainly DV avi's for a local tv station where the mpeg's are played out via an mpeg2 hardware card and stored for archive.

I've been asked if the mpeg's are "industry snardard" as there have been some issues playing back long mpeg2's via the hardware card (which is industry standard). yes and no; it depends what you call an "industry standard" most of the standard industry only use only "I" and "P" frame and constant GOP and constant bitrate for archiving (it's not better it's just more easy) with your parameters, you'll have only "I and P" frame (then compiliant with archiving and re-using but "bad" for commun end user)

Le 7 d?c. 05 ? 13:10, ffmpeg-user-request at mplayerhq.hu a ?crit : parameters for mastering dvd is not the same... ffmpeg don't manage to limit the bitrate (with the -maxrate parameter), if you're source is too complex (very complex like a video with moving white lines on a black background), ffmpeg make a "buffer underflow" (an error in reading the MPEG2 with a DVDplayer). You'll be no more MPEG2 compiliant. With the -trell parameter, you can limit this error (but just limit the number of errors not suppress), but you can generate too much little GOP (with 2 frames), it's not DVD compiliant too (min GOP is 3 frames) (and you still can have some "buffer underflow") Then no real issue... with ffmpeg you can't pipe to others tools (like the mjpegtools) with a sure result (headers are not always compatibles but it's possible to correct some of them with yuvcorrect), but with the export format "-f yuv4mpegpipe - | " you can decode the whole frame but pipe only the half of the frames to the output (it depends of your source, with the new divx container for example)

ffmpeg version CVS, build 3276800, Copyright (c) 2000-2004 Fabrice Bellard configuration: --prefix=/usr --enable-mp3lame --enable-libogg --enable-vorbis --enable-faad --enable-faac --enable-xvid --enable-a52 --enable-pp --enable-shared --enable-pthreads --enable-gpl built on Sep 20 2005 14:49:06, gcc: 3.3.6

Arguments:

fargs="-y -strict=1 -ilme -g 15

-r 25 -b 8000 -s 720x576 -vcodec mpeg2video -acodec mp2 ac3 is more compatible with most video players -ab 384 -ar 48000 -aspect 4:3" PS: dv is bottom field first, your MPEG2 stream will appear as

-g 15 is not respected (specially with "-ilme" a motion estimator for generate GOP according to the content of your source ;-)) progressive with your parameters (add "-top 0 ")

aargs="-y -acodec mp2 -ab 384 -ar 48000"

Many thanks,

Amadeus

PS: then ffmpeg is a great tool, but not completly pro (great for an personal use, but if you can't trust it at 100% it's not for professionnal use) PS: I'll prefer to talk in french too if you understand it ;-) bye Herv?