Can I reduce the bitrate by cropping the video?

[tetsuomaeda]

Hello!,

I have a question regarding the H.264 encoding using iMX6/VPU.

The original size of the video is 1920 x 1080, but the sky area is not necessary.

If we remove the sky area using "int avc_frameCroppingFlag" of "EncAvcParam" at the encoding, can we reduce the bitrate at the same picture quality?

Sorry for my primitive question because we have just started investigating the possibility of using iMX6 for our products.

Thanks in advance for your help.

Regards,

Tetsuo.

[joanxie]

do you want to change the Iframe and P frame size? I don't suggest that you do this, because if you change it, the quality will be worse, and you need to change the qt value.

[tetsuomaeda · Accepted solution]

Guanqiong-san,

Thank you for the response.

I might have misunderstood.

Following is the summary of my thought.

1.Upper 1/3 area (B) of the full screen (1920 x 1088) is not necessary

for our application.

Please refer to the attached PDF.

2. So, we would like not to assign the bits to this unnecessary area (B).

3. We think that, if we change the size of the area by "cropping" and

encode the necessary area (A) only, we can avoid assigning bits to the

unnecessary area (B) and can "save" the bits.

Is my thought correct?

I'd appreciate your feedback.

Regards,

Tetsuo Maeda

P.S. I'm sending this mail directly to you because I'm not sure how I

can attach a file at the community.

[tetsuomaeda]

Guanqiong-san,

Thank you for the response.

I might have misunderstood.

Following is the summary of my thought.

1.Upper 1/3 area (B) of the full screen (1920 x 1088) is not necessary for our application.

Please refer to the attached PDF.

2. So, we would like not to assign the bits to this unnecessary area (B).

3. We think that, if we change the size of the area by "cropping" and  encode the necessary area (A) only, we can avoid assigning bits to the unnecessary area (B) and can "save" the bits.

Is my thought correct?

I'd appreciate your feedback.

Regards,

Tetsuo Maeda