A mp4 file can contain ANY streaming content, i.e
audio/video in any codec.
The only thing that it's needed is a valid hint track where
it's specified
rtp data needed for streaming.
So, any streaming server (DSS for example) or app_mp4 can
read an mp4 file
and create the rtp packets with the correct timing
information without
knowing the format/codec of the media data. The only thing
that's needed is
something to create the mp4. For example rtpdump can create
a mp4 from any
ethereal capture with rtp traffic.
Both app_mp4 and app_rtsp just need to what codec is to map
the identifier to
the asterisk AST_FORMAT_XXX, and nothing more.
Also, app_mp4 could save any custom incomming data (in
theory) and save it as
a speciall hint track to be streamed later, but this way the
media track won't
be playable in a standar player, only streamed.
Once app_mp4 or app_rtsp receive an rtp packet they just
convert it to an
ast_frame, so asterisk can do whatever they need with it
(transcode for example).
Best regards
Sergio
---------- Original Message
----------------------------------
From: Klaus Darilion <klaus.mailinglists pernau.at>
Reply-To: Development discussion of video media support in
Asterisk<asterisk-videolists.digium.com>
Date: Fri, 20 Jul 2007 01:11:30 +0200
>Hi!
>
>AFAIK (please correct me when I am wrong) there are 3
different ways to
>get video into Asterisk:
>
>1. native Asterisk video support. Some applications like
voicemail,
>Playback and Background support recording/sending of
video. The video
>must be h263 or h264 in a proprietary Asterisk format.
This could be
>generated with ffasterisk or gstreamer (both methods are
quite
>complicated). Audio can be provided as .gsm or .wav. The
video will not
>be transcoded, thus the client has to support h263 or
h264
>
>2. app_mp4: The video must be in a .mp4 or .3gp
container with hinted
>audio+video tracks. Which Audio codecs are supported?
Which Video Codecs
>are support? Will app_mp4 make use of Asterisk's audio
transcoding
>capabilties? Video transcoding can be done explicitly
with app_transcode.
>
>3. app_rtsp: Asterisk will receive the video from a
streaming server
>(usually DSS). Which formats are supported? Can DSS
process any video
>formats or do we need to transform the video into .mp4
before giving it
>to DSS?
>
>IMHO a big problem is that there is no single common way
to generate
>video files for Asterisk and all the methods to generate
video are very
>complicated (except you can afford to by helix mobile
producer).
>
>comments, corrections and answers are very welcome
>thanks, klaus
>
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