i.MX6 video encoding specs

[egmedical]

I  have recently found out that the i.MX6 Family Comparison Table changed a lot between two revisions, and newer revisions claims more limited functionality than the older revision.

FLYRIMXPRDCMPR REV 15, available for example at: http://www.mouser.com/pdfDocs/Freescale_IMX_Family_Comparision.pdf

FLYRIMXPRDCMPR REV 16, available at: http://cache.freescale.com/files/32bit/doc/brochure/FLYRIMXPRDCMPR.pdf

(availability and said revisions confirmed on 01/23/2015)

Compare the two revision and pay attention to the changes, namely Hardware Video Acceleration row. We use the i.MX6 to do some 1080p video processing, therefore this functionality very important for us. But while the rev 15 claimed that the i.MX6 Solo is able to do 1080p30 video encoding, newer revision (rev 16) claims that only 720p encoding is supported. Did the Freescale just changed i.MX6 specifications?

The reference manual (i.MX 6Solo/6DualLite Applications Processor Reference Manual (rev. 1), currently available at http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6SDLRM.pdf) contains following:

Video Processing Unit (VPU), supports various decoding/encoding formats in

HW, up to 1080p plus SD 30fps decoding (H.264, VC1, RV10, DivX, etc.), and

up to 1080p 30fps encoding (H.264, etc.).

So it seems that the i.MX6 Solo should be able to do 1080p30 video encoding, but I really do not know if I can trust that information. If family comparison just changed, will the reference manual follow up?

We need to do 1080p30 video loopback (camera -> HDMI) and 1080p30 video encoding (using same camera) at the same time, possibly with minimum latency for the loopback. Is that even possible on i.MX6?

Thanks for any information, I will appreciate any help.

[igorpadykov]

Hi Ivo

you are right i.MX6 Solo is able to do 1080p30 video encoding, confirm

i.MX 6Solo/6DualLite Applications Processor Reference Manual is correct.

Best regards

igor

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[egmedical]

Hi Igor,

thank you for the clarification. Could you confirm if it is possible to do encoding and loopback (showing video on HDMI connected display) at the same time, or if that is beyond i.MX6 Solo performance?

Best regards

Ivo

[igorpadykov]

Hi Ivo

yes it is also supported.

Best regards

igor

[egmedical]

Hi Igor,

is there any kind of guide, tutorial of example code, how to achieve that?

We are able to do video loopback or video encoding using GStreamer. Unfortunately, it seems that mfw_isink element utilizes VPU (or bus, or memory?) too much, because the mxc_vpu_test.out reports significantly lower "enc fps" when the isink is active. The performance drop is so massive that we are not able to do 1080p25 (just 25 fps, not even 30) encoding to H.264.

On the other hand, when I tried to measure performance drop caused by running mxc_v4l2_overlay.out, there is also some performance drop, but the difference is much lower when compared to isink running. It seems that the mxc_v4l2_overlay.out is realized completely inside the i.MX6, so there is no need to utilize memory bus which could be bottleneck. Is there any way to use mxc_v4l2_overlay.out and GStreamer's mfw_v4lsrc at the same time, so we can do loopback and encoding at same time?

If you would like, I can share measurement method and results, so you can compare it to theoretical values.

Best regards

Ivo

[igorpadykov]

Hi Ivo

I think you can create new thread for this.

Thanks !

igor

[egmedical]

Ok, I posted detailed question to VPU perfomance on i.MX6 Solo (1080p30 encode + loopback).