About 2432 x 2048 MJPEG of IPNC

Hi Gomo

Look at ipnc 2.6.0 documentation :  Release_Notes_IPNC_DM36x.pdf, page 14 :

 • MegaPixel JPEG streaming at 5MP will not be played by ActiveX player due to limitation from RFC2435 (RTP Payload Format for JPEG-compressed Video)

_____

You could try rewrite  RTP receiving code in VLC.

Regards,
Marko.

Thanks for you reply!

 I had find some document about RFC2435,

3.1.5.  Width: 8 bits

   This field encodes the width of the image in 8-pixel multiples (e.g.,   a width of 40 denotes an image 320 pixels wide).  The maximum width    is 2040 pixels.

And it means 256 * (320/40) = 2048, have a multiple of 8 ; If we enlarge the  multiple to 16, the maximun width is 256 * 16 = 4096; 

Is it correctly?  I do not  understand the relationship completly.

Anybody can give me more information?  Or give me some advices to rewrite the RTP receiving?

Thanks a lot!

Since there is also a "0" number  in every numerical system,  you have to subtract base value (which is a multiply factor), that is :
2048 - 8 =2040
4096-16=4080

Yes, I know to subtract the base value.

I mean where to modify the base value? Can you give me more information?

Thans again！

VLC uses Live555 for RTP/RTSP.

You can look at Live555 source in a file  :  \live\liveMedia\JPEGVideoRTPSource.cpp,
where you can change that multiply factor (8).

  // There's at least 8-byte video-specific header

  /*

0                   1                   2                   3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Type-specific |              Fragment Offset                  |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|      Type     |       Q       |     Width     |     Height    |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  */

  if (packetSize < 8) return False;

  resultSpecialHeaderSize = 8;

  unsigned Offset = (unsigned)((DWORD)headerStart[1] << 16 | (DWORD)headerStart[2] << 8 | (DWORD)headerStart[3]);

  unsigned Type = (unsigned)headerStart[4];

  unsigned type = Type & 1;

  unsigned Q = (unsigned)headerStart[5];

  unsigned width = (unsigned)headerStart[6] * 8;

  unsigned height = (unsigned)headerStart[7] * 8;

  if ((width == 0 || height == 0) && fDefaultWidth != 0 && fDefaultHeight != 0) {

    // Use the default width and height parameters instead:

    width = fDefaultWidth;

    height = fDefaultHeight;

  }

  if (width == 0) width = 256*8; // special case

  if (height == 0) height = 256*8; // special case

  if (Type > 63) {

gomo said:

I modify the base value to 16, the client receive the width and height, and then multiply by 16. So the width and height can up to 4080 x 4080; It's enough to us.

Hello, gomo!

Can you share your patch?

Sorry, I have no patch.

I can show you how to modify:

Wis-streamer：

WISJPEGStreamSource.cpp  Line 143

/*
fLastHeight = (fBuffer[i+5]<<5)|(fBuffer[i+6]>>3);
fLastWidth = (fBuffer[i+7]<<5)|(fBuffer[i+8]>>3);
*/  

  int tHeight  = (fBuffer[i+5] << 8) | (fBuffer[i+6]);
  int tWidth = (fBuffer[i+7] << 8) | (fBuffer[i+8]);
if( tWidth < 2040);
{
   fLastHeight = (fBuffer[i+5]<<5)|(fBuffer[i+6]>>3);
   fLastWidth = (fBuffer[i+7]<<5)|(fBuffer[i+8]>>3);
}
else
{
   fLastHeight = tHeight /16;
   fLastWidth = tWidth /16;
 } 

Client: Live555,  JPEGVideoRTPSource.cpp  Function: processSpecialHeader

  unsigned width = (unsigned)headerStart[6] * 16;//8;
  unsigned height = (unsigned)headerStart[7] * 16;//8;

 We also meet a problem of MJPEG performace , See http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/100/t/149029.aspx

If you have good idea, please tell me! 

Gomo, your post all change?

I use it, but when I encode 5Mpx (2560x2048) I see only 1280x1024 on VLC 1.1.7

Hi,

    VLC can get 2048x2048 Mjpeg, you must modify VLC source of  receive header and rebuild.

   I did not modify the VLC, so you must do it by yourself. 

Ok, I set resolution to 2048x2048 and grab stream via openRTSP -m rtsrp://192.168.255.2/MJPEG (each frame to separate file) - file have resolution 1024x1024.

Set resolutin to 2048x2048, you can use VLC to get Mjpeg streamer;

And you can down to 2040x2040, and try again, 

My client player use appro's activex ffmpeg control, it seems not Live555 but ffmpeg decode the rtp packet. Unfortunatly, I can not find the rtp decoder code, who know where  is it such as

Live555,  JPEGVideoRTPSource.cpp  Function: processSpecialHeader

  unsigned width = (unsigned)headerStart[6] * 16;//8;
  unsigned height = (unsigned)headerStart[7] * 16;//8;

in ffmpeg

hi,gomo,

I have done you say above, the client the live555 transplantation to the MPlayer, live555 the following changes:

   JPEGVideoRTPSource.cpp 

  unsigned width = (unsigned)headerStart[6] * 16;
  unsigned height = (unsigned)headerStart[7] * 16;

 but the image is still not normal, my resolution is 2592 * 1920

can you give me more information?

thanks a lot!!

hi,gomo,

Now,I can display properly, but the image resolution is only 1296*960,

Please give me some help,thanks!

hi,

    Because the limitation of RFC2435, the largest size is 2048x2048 (256x8). So when your encode output is larger than 2048, you must change the ration.

    My resolution change ration 8 to 16. So in WISJPEGStreamSource.cpp,  we used our defined rule just like this.

/*
fLastHeight = (fBuffer[i+5]<<5)|(fBuffer[i+6]>>3);
fLastWidth = (fBuffer[i+7]<<5)|(fBuffer[i+8]>>3);
*/  

  int tHeight  = (fBuffer[i+5] << 8) | (fBuffer[i+6]);
  int tWidth = (fBuffer[i+7] << 8) | (fBuffer[i+8]);
if( tWidth < 2040);
{
   fLastHeight = (fBuffer[i+5]<<5)|(fBuffer[i+6]>>3);
   fLastWidth = (fBuffer[i+7]<<5)|(fBuffer[i+8]>>3);
}
else
{
   fLastHeight = tHeight /16;
   fLastWidth = tWidth /16;
 }

    In the client, we find the the place which parse the image resolution (w and h), add our defined rules, just like this

Client: Live555,  JPEGVideoRTPSource.cpp  Function: processSpecialHeader

  unsigned width = (unsigned)headerStart[6] * 16;//8;
  unsigned height = (unsigned)headerStart[7] * 16;//8;

 So whatever you use tools, your must modify the rules in C/S.

xiaofeng xu68950 said:

hi,gomo,

I have done you say above, the client the live555 transplantation to the MPlayer, live555 the following changes:

   JPEGVideoRTPSource.cpp 

  unsigned width = (unsigned)headerStart[6] * 16;
  unsigned height = (unsigned)headerStart[7] * 16;

 but the image is still not normal, my resolution is 2592 * 1920

can you give me more information?

thanks a lot!!

Look the image, the resolution is still not correct.

You must check again. And you can save snap image from the Live555 directly, and use tool(WinHex) to modify the Jpeg resolution( w and H) by manual and the see the image whether is ok.

Glad to receive your reply,

In accordance with what you said, Now, Images can already be displayed properly, but I found the images show only the source data (2592 * 1920)half of the image (1296 *960), 

I do not know how to modify.

can you give me some help?Thanks again

1)Save a pic

 2)google to find the JPEG format, 

 3)use a tool (such ad WinHex) to go to the width and height,

 4)modify the value to  2592  1920, and save as

 5)use the image tool to open.

 6)See the picture whether is correct.  If the image is correct, It prove the resolution of parse  is wrong in the client.