[Live-devel] How to re transmit

[Matt Schuckmann]

There are more advanced options, depending on your h.264 encoder. For 
example the TI h.264 encoder supports a couple of features, Temporal 
Scalability and  Chain Free P Frame encoding.
http://processors.wiki.ti.com/index.php/H.264_DM36x_Ver_2.0_Codec#Scalable_video_coding_.E2.80.93_Temporal
http://processors.wiki.ti.com/index.php/H.264_DM36x_Ver_2.0_Codec#Chain_Free_P_frame_encoding

Both of which allow one to transmit and decode some subset of the 
encoded bit stream, usually on some even multiple of the key frame 
frequency.

Both of these methods requires you to know or at least discover some 
pretty detailed information about the bit stream you are retransmitting 
but it can be done.

Matt S.

On 10/14/2012 6:24 AM, Jeff Shanab wrote:
> In the simplest case, H264 defines a protocol that starts with a key 
> frame and has a succession of difference frames that are much smaller. 
> ie the 24KByte key frame has all the information needed to draw the 
> whole frame and the 1Kbyte diff frame has only the changes needed to 
> update the key frame to the new display frame.
> The first difference frame depends on the key frame and each diff 
> frame depends on the key frame and the changes made by all the 
> proceeding diff frames.
>
> One trick would be to have a key frame per second and send and display 
> only keyframes.
> But since the keyframes are big you can expect at most a 60% reduction 
> on 30fps video.
>
> Anything else is transcoding. Decode the video at the source fps and 
> re-encode at the fps you want to display.
> This can be done in software with libavcodec, but it takes CPU!
> This also would let you reduce the resolution, sometimes the client is 
> not viewing it at full resolution and that effects bandwidth considerably.
> ------------------------------------------------------------------------
> *From:* live-devel-bounces at ns.live555.com 
> [live-devel-bounces at ns.live555.com] on behalf of Tarun Batra 
> [tbatra18 at gmail.com]
> *Sent:* Thursday, October 11, 2012 10:20 AM
> *To:* live-devel at ns.live555.com
> *Subject:* [Live-devel] How to re transmit
>
> Hello Sir,
>
>      I have implemented "testOnDemandRTSPServer" on my machine which 
> receives h264 transport stream from my streamer application.
>
>      Is there any way to re transmit this received stream from 
> streamer, to my RTSP clients with different fame rates? As some of my 
> RTSP clients do not have sufficient bandwidth to receive stream with 
> high frame rate. My streamer uses MPEG1or2VideoStreamDiscreteFramer to 
> stream a video from digital camera.
>
>
>
> _______________________________________________
> live-devel mailing list
> live-devel at lists.live555.com
> http://lists.live555.com/mailman/listinfo/live-devel

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.live555.com/pipermail/live-devel/attachments/20121015/3df8c3a6/attachment.html>