readme

网络MPEG4IP流媒体开发源代码

web cams, but most likely not regular capture cards).

Use with QT 6.0 and Real One
============================

It is possible to create content for QT 6.0 and Real One with the 
Envivio plug in.  You must create with the audio encoding set to 
AAC for both of these.  

If you want to stream (using the instructions below), you must have
Envivio version 1.2.  Download Real One, then download Envivio TV
version 1.2 afterwards.  The Envivio plugin downloaded with Real One
will not play multiple AAC frames in a RTP packet, so your sound will
appear to stutter.


Network Transmission
====================

To use mp4live to transmit live audio/video to the network, follow these
directions: 

Select 'Enabled' in the Transmission section of the main window.

By default, mp4live will multicast the media to IP address 224.1.2.3

If you wish to change this, select the 'Settings...' button in the
Transmission section of the main window. A dialog will appear that allows
selection of the destination IP address (either unicast or multicast),
the UDP port numbers used, the TTL used if multicasting, and the name of
the .sdp file to generate (more about that in a minute). When you're done
making changes, select 'OK'.

When you press mp4live's 'Start' button, media transmission to the network 
will begin. Also a small text file with extension .sdp will be created that 
describes the media transmission for the player. The player needs the .sdp 
file to be able to tune into the media streams. (Note the .sdp file can also
be generated from the Transmission Settings dialog)

The most convenient way to distribute the .sdp file is to have mp4live write
it to a directory that is accessible from a web server (httpd) that is running
on the same machine as mp4live. This allows the client to be started with
the HTTP URL of the sdp file, and it will download the .sdp file via http
and then use the information in the .sdp file to tune into the network
transmission. E.g. 'gmp4player http://myserver/myprogram.sdp'

For Real One, use the Open command with http://myserver/myprogram.sdp.  For
QT6.0, use Open URL.

You can of course distribute the .sdp file in a number of other ways, say
ftp, or email. You would then start the player with the local file name 
of the sdp file, e.g. 'gmp4player myprogram.sdp'


Use with Darwin Streaming Server
================================

If you would like to use mp4live in conjunction with the Darwin Streaming
Server (DSS), that is easy to do. You can have mp4live both record and 
transmit live media streams. When you record the .mp4 files, just ensure 
that they are written to the media directory that is accessible via the Darwin 
Streaming Server, typically /usr/local/movies. Once the recording is complete,
it will be available for on-demand playback.

For example: $ gmp4player rtsp://DSS/mymovie.mp4

The Darwin Streaming Server can also be configured to act as a relay agent
for the mp4live media streams. Copy the .sdp file generated by mp4live to
the media directory of the Darwin Streaming Server (e.g. /usr/local/movies)
Players can now request the .sdp file from DSS which will cause DSS to act
as a relay between mp4live and the player.

For example: $ gmp4player rtsp://DSS/mymovie.sdp


Sharing Capture Cards
=====================

If you have another program that wants to simultaneously process the raw
audio and/or video from the capture cards, there is typically a problem
in that many drivers only support one reader at a time. To address this
issue, mp4live can be configure to write the raw audio and/or video that
it reads from the capture cards to a named pipe (fifo). A named pipe looks
like a file, but the data only exists in memory and never goes to disk.
This is an efficient way to have the two applications share the media data. 

To configure this feaure, add the following to ~/.mp4live_rc (or whatever
configuration file you want to use), changing "/dir" to some directory 
where you want the named pipes to exist:

rawEnable=1
rawAudioFile=/dir/audio_pipe
rawAudioUseFifo=1 
rawVideoFile=/dir/video_pipe
rawVideoUseFifo=1 

The audio format is 16 bit PCM, the video format is YUV12 (planar 4:2:0 YUV).

Command Line Options
====================

There are currently four command line options to mp4live:
--file <config-file>
--automatic
--headless
--sdp

--file <config-file> allows specification of the mp4live configuration file
to something other than ~/.mp4live_rc. Perhaps you have a several frequently
used configurations. You can save the configuration settings to different
files, and then use this option to choose among them.

--automatic causes mp4live to act as if the Start button was pressed
immediately upon startup. The program will do whatever the current 
configuration instructs it to do. This option can be used in conjunction
with the 'cron' utlity to do scheduled recording and/or transmission.

--headless causes mp4live to behave in the --automatic mode AND not display
any user interface.

--sdp causes mp4live to just generate the sdp file based on its configuration
file and then exit.


Known Issues
============

Using a system with a PCI instead of an AGP video display card can cause 
video "tearing" with CIF or larger size images. I.e. the PCI bus quickly
gets swamped moving raw video from the video capture card to the CPU, and 
then from the CPU to the video display card. Having the AGP bus for the
CPU to video display card transfer alleviates this problem. If someone is
interested one could experiment with the video overlay capabilities of the
Bt8x8 to bypass this problem, but it would require some rework of our code
with respect to the video preview function.

It took me awhile to figure this out so perhaps I can save some of you some
time. If you use the Hauppage WinTV Go card you need to connect the mini-jack
on the card to the line-in input on your sound card in order to get the
audio signal from the TV tuner.

Note there is currently no support for DV/mini-DV camcorders via FireWire. 
You can of course still use these via their composite or S-Video outputs.

More recent versions of mp4live add streaming hint tracks as a post-processing
step (i.e. after the recording is finished). For long duration recording
(1 hour or greater), this step can take a minute or two. I'm hoping to 
enhance the UI to provide user feedback while this is taking place, but
for now the application gets very unresponsive during this period. If this
is a big problem for you, there is a configuration option to disable the
hinting process, "recordMp4HintTracks=0". The mp4 file can always be hinted
later with the mp4creator utility.

We know that the audio and video goes out of sync.  This is due to 
deficiencies in the drivers (video for linux, OSS) that we are using.

We've made fixes so that the latest OSS drivers will help (the ones with
SNDCTL_DSP_GETERROR defined), and the Video for Linux 2 driver would help, 
but we can't figure out how to install that driver on our machine.  If you're
in the San Jose area and can help, come on by.

Unknowns
========

I've only used mp4live with two video capture cards the Viewcast Osprey 100
and the Hauppage WinTV Go. There are many other Bt8x8 based capture cards 
listed in the bttv driver documentation. Odds are you're using one of these ;-)
Reports from initial users suggest though that the bttv driver handles the
wide variety of cards gracefully, and mp4live doesn't have card specific 
issues.

If you do have problems with mp4live, my first suggestion is that you download 
the latest version of the xawtv package, and try it with your capture card. 
If it works and mp4live doesn't then I'd be glad to hear from you. If xawtv 
doesn't work with your capture card, then I can't help you. Something is 
wrong with your capture card/system/bttv driver/kernel combination. I don't
have the capability or inclination to debug that for you! 


Links
=====
MPEG4IP			http://www.mpeg4ip.net/
bttv driver		http://bytesex.org/bttv/
qce driver		http://www.sourceforge.net/projects/qce-ga
xawtv			http://bytesex.org/xawtv/
Xvid			http://www.xvid.org/
LAME			http://www.sourceforge.net/projects/lame


Dave Mackie
Cisco Systems, Inc.