4 - D1 decode with DM368

John,

It is marginally possible to get 4CH decode on DM368, but before commenting on that, i would like to understand the exact usecase. Can you tell me what all would you need to be done from DDR perspective (like resize the SD decoded output to other resolutions...)? Also, are you looking for universal decoder?

Regards,

Anshuman

Hi Anshuman,

We would be decoding H264, MPEG-4, or MPEG-2.  With the highest priority being H.264.  If the initial resolutions were less than SD  (720x480), then we would scale up to SD.  However, if it were a requirement to only decode SD and have no scaling, then I would take that into consideration.  So SD decode and SD display on 4 composite outputs would be the minimum requirement.

John A

Hi John,

John Anderson said:

So SD decode and SD display on 4 composite outputs would be the minimum requirement.

How are you planning to get 4 composite outputs?

Also, what is the plan for universal decode requirement? With universal decode, 4 D1 realtime decode might not be possible.

Regards,

Anshuman

Anshuman Saxena said:

Hi John,

So SD decode and SD display on 4 composite outputs would be the minimum requirement.

How are you planning to get 4 composite outputs?[/quote]That's the question I hoped to get answered by posting here.

Anshuman Saxena said:

Also, what is the plan for universal decode requirement? With universal decode, 4 D1 realtime decode might not be possible.

I don't mean to sound dense but I described the decode requirements (4 SD streams of either H264, MPEG-4, or MPEG-2).  So I guess I have to ask... What's "universal" decode?

John A

 

John Anderson said:

Hi John,

So SD decode and SD display on 4 composite outputs would be the minimum requirement.

How are you planning to get 4 composite outputs?[/quote]That's the question I hoped to get answered by posting here.

[/quote]

DM368 has single VENC that can generate one composite output. The other option would be to do some multiplexing of 4 streams and pass it over digital output interface at 4 times the clock and use external FPGA + external VENCs to demultiplex these 4 streams and pass to the composite outputs.

The above approach would need a decent amount of work and also it is more of concept. Our drivers/software stack does not support any such thing directly.

John Anderson said:

I don't mean to sound dense but I described the decode requirements (4 SD streams of either H264, MPEG-4, or MPEG-2).  So I guess I have to ask... What's "universal" decode?

 "Universal Decoding" for H.264 decoder would mean that the decoder can decode any kind of H.264 content. This would mean that decoder has to support most of the tools. The other option is a closed loop decoder, where we ensure that H.264 decoder can decode all the content that our H.264 encoder has encoded. This would mean we dont need to support the tools in the decoder which our encoder does not use. It helps in gaining performance.

Similar thing is true for MPEG4 also.

For your use case, where streams can be H.264, MPEG4 or MPEG2, they all need to be decoded using different decoders. The parser need to understand the kind of compression and use the respective decoder.

I hope it makes things clearer.

Regards,

Anshuman