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DM6467 EVM h.264 BP decoder decodes interlaced video clip

As far as I know, BP h.264 decoder cannot handle encoded interlaced video data.

However, using the decode demo of DM6467 EVM with the clip dust_1080i_30fps.264 is successful and the clip is decoded properly.

How?

  • This is a good question, and it is making the rounds internally so hopefully we will have a more solid answer for this soon. My initial suspicion is that the codec just treats the incoming 1080i60 as 1080p30 and does a blind decode with no real deinterlacing (the output appears to have horizontal motion tearing artifacts as seen with a weaving deinterlace), but this is really just a guess.

  • This is confirmed, if you analyze the dust.264 stream it is in fact a progressive stream, so the 1080i was just referring to the original 1080i60 content that looks to have been fed into the encoder as a 1080p30 stream.

    The only problem with this is codec performance, as if you take a weave deinterlaced frame and feed it into the codec as progressive the codec will typically have a harder time finding motion vectors (as every other line is from a different time) so you end up with fewer predicted frames, if the codec was capible of true interlaced content it would be able to seperate the stream into the two individual fields for each frame and find the motion vectors for them independently making the codec far more efficient.

  • Dear Nir Aloni:

    Could you tell me where I can find the decoder demo program?

    Or Could you share your demo decoder program to me?

    I want to understand the decoder and tune it, thank you a lot.

    ---

    Best Regards,

    Wang

     

  • The decoder is part of TI's DVSDK 1_40_02_33.

    After installing it on linux, you can find it in:dvsdk_1_40_02_33/dvsdk_demos_1_40_00_18/dm6467/decode.