Hello, I'm new to the list, so if this is an FAQ, please point me to the relevant docs. I'm playing with Theora, to see what kind of quality I can expect (I realise its not for production use yet). I've download the source from CVS, and got it to build, with the example encoder and player. While trying to find something to serve as a good source of input, I decided I'd use a DVD, since the input would be of a good quality. Since dumping the stream to a yuv4mpeg file is prohibitively expensive on my system (no where near enough room), I decided I'd try encoding from two fifos. I set up mplayer to give me the output cd /tmp mkfifo stream.yuv mkfifo audiodump.wav mplayer -dvd 2 -vo yuv4mpeg -ao pcm That part works fine. I then set up encoder_example as follows cd /tmp encoder_example -a 3 -v 7 stream.yuv audiodump.wav It correctly identifies the input streams (and therefore can read correctly), however, when it gets to its compression loop, it blocks. I tried setting up mplayer as the reader also mplayer -audiofile /tmp/audiodump.wav /tmp/stream.yuv It start correctly, and brings up the viewing window, but doesn't start to play (I'm just left with a black screen) Finally, I try using cat, just to make sure the source mplayer isn't at fault cat /tmp/audiodump.wav > foo & cat /tmp/stream.yuv > bar & And the files grow and grow, so that works ok. I think perhaps encoder_example is trying to seek in the stream perhaps. Has anyone done this before? Thanks -- Cameron Kerr Email: cameron.kerr@paradise.net.nz Website: http://nzgeeks.org/cameron/ --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'theora-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.
On Sunday 02 February 2003 06:57 pm, Cameron Kerr wrote:> Hello, I'm new to the list, so if this is an FAQ, please point me to the > relevant docs. > > I'm playing with Theora, to see what kind of quality I can expect (I > realise its not for production use yet). I've download the source from > CVS, and got it to build, with the example encoder and player.[...]> cd /tmp > mkfifo stream.yuv > mkfifo audiodump.wav > mplayer -dvd 2 -vo yuv4mpeg -ao pcm > > That part works fine. > > I then set up encoder_example as follows > > cd /tmp > encoder_example -a 3 -v 7 stream.yuv audiodump.wav > > It correctly identifies the input streams (and therefore can read > correctly), however, when it gets to its compression loop, it blocks.[...] I ran into the same problem initially. It seems (I'm guessing) that the 4-month-old example encoder needs to get the packets from video and audio initially in a particular order, and mplayer is starting with them in a different order (i.e. encoder_example may want the first video packet and then the first audio packet, but mplayer is sending the first audio packet and then the first video packet, perhaps?) and you end up with encoder_example waiting for a packet from mplayer before it can take the next packet off of the fifo, and mplayer is waiting for a packet to be taken off of the fifo before sending any more... The work-around for me was to use TWO mplayer instances - one exporting only the audio and another exporting only the video. That seemed to get it going. You can find a slightly rambling but maybe-helpful "HOWTO" file for the Alpha 1 release at: http://www.dogphilosophy.net/SECTION-Technical_Stuff/ogg-theora-microhowto.html Let me know if it's helpful... I SUSPECT a lot of the issues in the Alpha 1 release will be nicely handled when the next release finally comes out. Right now it's scheduled to be Beta 1 sometime in March, though I don't know if it's on track to be out by then or not. --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'theora-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.
the alpha is about as far from an optimized player as you can get. It's all
C, there is lots of buffer copies, and no effort has yet been made to make sure
all cards are getting YUV overlays, etc.
If you're concerned about how this will perform, look at the original VP3
codecs instead.
-----Original Message-----
From: Cameron Kerr [mailto:cameron.kerr@paradise.net.nz]
Sent: Mon 2/3/2003 7:42 PM
To: theora@xiph.org
Cc:
Subject: Re: [theora] Encoding from fifo's
On Mon, Feb 03, 2003 at 10:18:01AM -0700, emaillist+ot@dogphilosophy.net
wrote:
> The work-around for me was to use TWO mplayer instances - one exporting
only
> the audio and another exporting only the video. That seemed to get it
going.
Alas, the encode plays back terribly on my PIII 800 system, although
there are no artifacts (quality looks damn fine actually), the playback
speed is just not suitable. I got large frequent slowdowns in playback,
a little like someone who suffers from stuttering (but without the
repitition).
I tried encoding the same source (a dvd), in Vorbis+Theora, and again in
MP3+MPEG4. These are the commands I used
cd /tmp/
mkfifo audiodump.wav
mkfifo stream.yuv
mplayer -dvd 2 -vo yuv4mpeg -au null &
mplayer -dvd 2 -vo null -au pcm &
encoder_example -a 2 -v 5 stream.yuv audiodump.wav > test.ogm
It didn't get it all done however, I had errors from mplayer such as
the
following:
Too many audio packets in the buffer: (4096 in 8257536 bytes).
Maybe you are playing a non-interleaved stream/file or the codec failed?
For AVI files, try to force non-interleaved mode with the -ni option.
I then repeated the experiment with mencoder
mplayer -dvd 2 -vo yuv4mpeg -au null &
mplayer -dvd 2 -vo null -au pcm &
mencoder -o test.avi -ovc lavc \
-lavcopts vcodec=mpeg4:vbitrate=1800:vhq \
-oac mp3lame -lameopts preset=standard \
-audiofile audiodump.wav stream.yuv
Which plays back fine. I still get the errors from mplayer however.
I also tried extracting the audio first to a seperate file, then reading
the video in a seperate pass straight from the dvd (via mplayer). This
gave the same (unsuitable in Theora) results, but managed to encode the
entire input.
Any ideas why I get these mysterious stalls? Both encoders seem to be
doing about the same fps (~8fps).
--
Cameron Kerr
Email: cameron.kerr@paradise.net.nz
Website: http://nzgeeks.org/cameron/
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