i.MX Processors中的主题 Re: Maximum bit rate for H.264 encoding by VPU?

Maximum bit rate for H.264 encoding by VPU?

tetsuomaeda — Tue, 14 Apr 2015 04:12:59 GMT

Hi.

I'm trying to understand the picture quality of H.264 video encoded by iMX6/VPU before we decide to use iMX6 in our platform.

Do you know the maximum bit rate of the H.264 stream that is encoded by VPU?

"IMX6SDLRM_Reference_manual" says that the bitrate is 14Mbps in Table 9-8. on page 479.

Is it actually the maximum bit rate?

I'd appreciate it if you tell me the item (such as VPU clock, bus traffic or memory access) that decides the maximum bit rate as well.

Regards,

Re: Maximum bit rate for H.264 encoding by VPU?

Yuri — Tue, 14 Apr 2015 06:29:02 GMT

"Normally, the limitation comes from many factors, e.g., DDR bandwidth, encoder HW limitation, display capability, video content, etc.

For example, the maximum limitation for iMX6Q VPU alone should be able to do dual channel 1080p@30fps for some of the video clips

at VPU=264MHz. However, we cannot claim we can support dual 1080p@30fps decoding because we cannot decode dual channel blu-ray

clips which may have the maximum bitrate up to 40MHz for each channel. In addition, even for normal video clips, we may still have problem

to do dual channel but depends on whether other post-processing e.g., resize, or deinterlacing for interlaced video, is needed. "

Have a great day,
Yuri

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: Maximum bit rate for H.264 encoding by VPU?

tetsuomaeda — Tue, 14 Apr 2015 07:11:34 GMT

Yuri-san,

Thank you very much for your prompt response.

We are thinking to use iMX6 just for H.264 encoding of 1080p video at 30 fps.

We understand that higher bitrate results better picture quality and would like to know the limitation of the bitrate.

I understand that the bitrate depends on the complexity of the video, but there would be some limitation of the bitrate even if VPU is working only for the encoding.

At that time, no other task would be necessary except the system task such as OS.

Is it difficult to say the maximum output bitrate of the H264 encoder even if all the resources are working for the encoding?

Accuracy is not necessary at this moment and we would like to know the approximate value.

I'd appreciate your help.

Regards,

Tetsuo,

Re: Maximum bit rate for H.264 encoding by VPU?

Yuri — Thu, 16 Apr 2015 10:34:31 GMT

Tetsuo, hello !

The VPU is third pary IP and its detailed specifications are not provided, sorry.

Regads,

Yuri

Re: Maximum bit rate for H.264 encoding by VPU?

joanxie — Thu, 16 Apr 2015 10:56:33 GMT

pls refer to the enclosed vpu pefermance file.

Re: Maximum bit rate for H.264 encoding by VPU?

tetsuomaeda — Thu, 16 Apr 2015 12:13:46 GMT

Hi Guanqiong,

Thank you for the information.

I'll consider it in our investigation.

Regards,

Tetsuo Maeda