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Encoding SEI Picture timing timecode.

James Curran
Prodigy 35 points

Hello,

I am trying to encode a timecode as per:
processors.wiki.ti.com/.../DM36x_H.264_encoder_FAQ

I set the time code field to a value and then having encoded it using VIDENC1_process on the DM368 I am then trying to decode it with
ffmpeg. I am unable to extract the timecode I have set.

The parameters I am using are:


  /* Encapsulate generic parameters inside the H264 specific parameters structures
   * and pass to encoder init. */
  h264params.videncParams     = *params;
  h264params.videncParams.size    = sizeof(h264params);
  h264params.numTemporalLayers    = 0;
  h264params.profileIdc      = 66; /* base profile 66 */
  h264params.entropyMode      = 0;
  h264params.transform8x8FlagInterFrame  = 0;
  h264params.transform8x8FlagIntraFrame  = 0;
  h264params.seqScalingFlag     = 0;
  h264params.levelIdc      = 30;
  h264params.encQuality     = 2;
  h264params.enableARM926Tcm    = 0;
  h264params.enableDDRbuff    = 0;
  h264params.enableVUIparams    = 1;


  h264dparams.videncDynamicParams    = *dynParams;
  h264dparams.videncDynamicParams.size   = sizeof(h264dparams);
  h264dparams.enableBufSEI      = 1;
  h264dparams.enablePicTimSEI     = 1;
  h264dparams.VUI_Buffer       = &H264VENC_TI_VUIPARAMBUFFER; //&VUIPARAMBUFFER;
  h264dparams.VUI_Buffer->numUnitsInTicks  = 1;
  h264dparams.VUI_Buffer->timeScale    = 30;
  h264dparams.VUI_Buffer->picStructPresentFlag = 1;

I have changed Venc1_process to give a constant timestamp:


    inArgs.videncInArgs.size                         = sizeof(IH264VENC_InArgs);
    inArgs.videncInArgs.inputID                      = GETID(Buffer_getId(hInBuf));


    /* topFieldFirstFlag is hardcoded. Used only for interlaced content */
    inArgs.videncInArgs.topFieldFirstFlag            = 1;
   
    outArgs.videncOutArgs.size                        = sizeof(IH264VENC_OutArgs);


    inArgs.insertUserData = FALSE;
    inArgs.lengthUserData = 0;

    inArgs.timeStamp = 0xAABBCCDD;

    /* Encode video buffer */
    status = VIDENC1_process(hVe->hEncode, &inBufDesc, &outBufDesc, (VIDENC1_InArgs *)&inArgs,
      (VIDENC1_OutArgs *)&outArgs);

I have tried to encode user unregistered data and I can decode this without issue using ffmpeg.
I am trying to do the same with SEI picture timing.
I recompiled ffmpeg to put in some debug to print out what is decoded. When I decode the stream I see the picture timing NAL
but the flag sps->pic_struct_present_flag is not set. Should it be set? How do I get the timecode out of the stream?
Can I expect to see 0xAABBCCDD somewhere?

I say "I see the picture timing NAL " - what this means is that a function called decode_picture_timing is called in  ffmpeg when the frame
is decoded.

Is there something obvious wrong?

We want to be able to put a 32 bit timecode as per the STANAG 4609 spec that states:

The H.264 format, specified in [11] provides for an optional time stamp to be
defined in the Supplemental Enhancement Information (SEI) Message. The “picture
timing SEI message” (pic_timing) specifies the time as HH:MM:SS:FF. It is a persistent
time stamp that reflects the time of frame capture, and it also contains flags to specify
whether the video is drop-frame, and whether there is a discontinuity in the video time
line.

Also I read this:

http://processors.wiki.ti.com/index.php/DM36x_Interlace_Encoding_FAQs

 

We are using DM 368.

 

This section:
 What all feature set of encoder is disabled when interlace encoding is enabled?

Following are the limitations of the encoder:

    • No Baseline Profile: Fatal error (IH264VENC_ERR_INTERLACE_IN_BP) is returned during algInit() instance creation stage if application tries to encode interlaced content in Baseline Profile mode.
    • Airrate: This feature is not supported for interlaced content
    • EncoderLevel: If interlace encoding is enabled for levels less than 2,1 or level more than level 4.1 encoder will return fatal error during instance creation.
    • Rate Control Algorithms: CBR and Custom CBR1 Rate Control algorithms are not supported for interlaced encoding and will be automatically disabled by encoder.
    • Buffering period SEI: Buffering period SEI insertion is not supported for interlaced content
    • Picture Timing SEI: Picture Timing SEI insertion is not supported for interlaced content

Is this the issue? I am pretty sure we are producing interlaced video, so this is an encoder limitation?