[Live-devel] Starting Frames are corrupted

[Vikram Singh]

On a further note : 

 

-        I was testing the same file with wowza streaming server and I did
not find any glitches at the start.

 

-        But the same file when I am streaming with directly downloaded file
testH264VideoStreamer.exe provided in the testprogs of live555 library,

the stream starting was very noisy as shown in the links from previous
emails.

 

-        I also found the same starting frame issues with Darwin streaming
server when I was streaming with the same file.

 

-        And I am sure the files I am testing with are not corrupted.

 

-vikram singh

 

From: live-devel [mailto:live-devel-bounces at ns.live555.com] On Behalf Of
Vikram Singh
Sent: Friday, June 20, 2014 7:58 PM
To: 'LIVE555 Streaming Media - development & use'
Subject: Re: [Live-devel] Starting Frames are corrupted

 

Hi ross,

 

Please ignore my previous mail. I was sent accidently.

 

Just for testing purpose, I have reduced my streaming video size to 100*100
px size.

By reducing the size I want to avoid the scenario where on the client side
there is truncation of data, due to buffer overflow in the starting.

This buffer overflow was assumed because the client had no idea about server
frame size and initialized a default size to the buffer that receives data.

Even then I have the problem of corrupt frames in the starting.

 

Can there be any other case because of which this initial corruption of
frames is happening.

 

An another observation is when I had incorrect OutPacketBuffer::maxSize
initialized to it, the frame rendered were like this

https://drive.google.com/file/d/0B9yXmUZbfI7_OWJiblZta1hXYWM/edit?usp=sharin
g

i.e the frame would bleed to the bottom and that symbolizes the truncation
of frame.

 

Instead the corruption was something like this

https://docs.google.com/file/d/0B9yXmUZbfI7_YUxEb1ltZ2pwa3M/edit

 

and after some time it would clear up like this

https://docs.google.com/file/d/0B9yXmUZbfI7_VW9uU2NWU041SkE/edit

 

So can there be any other issue that is causing this problem.

-vikram

 

From: live-devel [mailto:live-devel-bounces at ns.live555.com] On Behalf Of
Ross Finlayson
Sent: Wednesday, June 18, 2014 11:13 PM
To: LIVE555 Streaming Media - development & use
Subject: Re: [Live-devel] Starting Frames are corrupted

 

I am having --  unsigned OutPacketBuffer::maxSize = 900000;  in
mediaSink.cpp

If I decrease the maxSize then the frames I get are truncated.

 

OK, there are two separate buffer sizes that you need to concern yourself
with.

 

"OutPacketBuffer::maxSize" is the buffer size that is used - by your server
- when *transmitting* NAL units.  You must set it to be at least as large as
your largest NAL unit.  Otherwise you will see (in 'stderr') error messages
about needing to increase "OutPacketBuffer::maxSize".

 

The receiving application - in your case VLC - must also have sufficient
buffer space to be able to reassemble the incoming RTP packets into a
complete NAL unit.  That is what I referred to in my previous email message.

 

In any case, 900000 bytes is an *insanely large* NAL unit (I-frame) size!!
A NAL unit this large will get fragmented into *60* RTP packets, and *all*
of these RTP packets must be received by the receiving application,
otherwise the entire frame will be unrenderable.  This is why it's much
better to reconfigure your encoder so that it breaks up large I-frames into
smaller 'slice' NAL units.

 

 

 Can you please specify how to decrease the nal unit size without decreasing
the value of maxSize.

 

You mean "how to decrease the nal unit size without *increasing* the value
of maxSize"?  Once again, you need to reconfigure your encoder to break up
large I-frames into smaller 'slice' NAL units.

 

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/ 

 

 

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