DSP Alg as part of the link chain

Amit Porat

We would like to use the DSP to modify the input video buffer, and afterwards display and encoded the modified video.

The DspAlg is configured as a process link, where it gets frames queue in but does not queue out frames.

The problem with this configuration is we suspect the following links on the chain are not synchronized with the DspAlg process. After the dsp there are dup links and possibly the dup links are copying the memory before the dsp has had a chance to modify the content.

Is it possible to create a frame out queue attached to the DspAlg link? (to use the dsp link not from the process link of ipcframesout but from the out link of ipcframes out?)

Or should I solve this issue by adding messages and signaling the following link that it can continue?

thanks!

over 11 years ago

0 Badri Narayanan over 11 years ago

TI__Guru 59700 points

The nextLink after ipcFramesOutLink will NOT receive the frame until processLink has returned the buffer. ProcessLink will return the buffer only after algLink has completed processing the frame.The problem you are seeing is not due to use of processLink and adding output frame queue to algLink will not resolve the issue. What is the actual issue you are seeing ?

0 Aaron Lieber over 11 years ago in reply to Badri Narayanan

Prodigy 160 points

Hi Badri,

We see in the file ipcFramesOutLink_tsk.c in function

Void IpcFramesOutLink_tskMain(struct Utils_TskHndl * pTsk, Utils_MsgHndl * pMsg)

case SYSTEM_CMD_NEW_DATA:
Utils_tskAckOrFreeMsg(pMsg, status);

                IpcFramesOutLink_processFrameBufs(pObj);
                IpcFramesOutLink_releaseFrameBufs(pObj);
                break;

and inside IpcFramesOutLink_processFrameBufs()

        if (pObj->createArgs.baseCreateParams.processLink != SYSTEM_LINK_ID_INVALID)
        {
            if (pObj->createArgs.baseCreateParams.notifyProcessLink)
            {
                System_ipcSendNotify(pObj->createArgs.baseCreateParams.processLink);
            }
        }
        else
        {
            for (queId = 0; queId < pObj->createArgs.baseCreateParams.numOutQue; queId++)
            {
                if ((pObj->createArgs.baseCreateParams.notifyNextLink) && (sendMsgToTsk & 0x1))
                {
                    System_ipcSendNotify(pObj->createArgs.baseCreateParams.outQueParams[queId].
                        nextLink);
                }
                sendMsgToTsk >>= 1;
                if (sendMsgToTsk == 0)
                    break;
            }
        }

If I understand correctly, the process link gets notified and not the out link, however immediately after this notification the buffers get released by IpcFramesOutLink_releaseFrameBufs

We are trying to copy parts of images between channels, we see that when we copy parts of the image to a temp buffer, and then copy the buffer onto an image from another channel, that it only works some of the time resulting in a flashing kind of image in the output video. However when we stop with a breakpoint using the JTAG it always works, so we think this is a timing or some other kind of memory issue where we are not writing to the correct memory corresponding to the video of the channel because it has already been released and reassigned.

0 Badri Narayanan over 11 years ago in reply to Aaron Lieber

TI__Guru 59700 points

IpcLinks are connected to exchange frames across cores using ListMP. ListMp is a multi core linked list

Below is the sequence of steps that take place to exchange frames between ipcFrames links

IpcFramesOut

Put frame pointer into tail of ListMPOut

ipcFramesIn

Get frame pointer from head of ListMPOut

Forward the frame pointer to nextLink

When nextLink frees the frame put frame pointer into tail of ListMPIn

ipcFramesOut

Get freed frames from head of ListMPIn

Forward the freed frame to nextLink.

As you can see releaseFrameBufs will get freed frames from ListMPIn and then forward it.There is no chance of ipcFrames forwarding a frame that is not processed by processLink.

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DSP Alg as part of the link chain