Why does the decoder need so many capture buffers?

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
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1

Hi,

I test the 00_video_decode with the cmd:
./video_decode H264 --disable-rendering -o out.yuv test.264
test.264 (9.7 MB)

and the min_dec_capture_buffers is 18 after
ret = dec->getMinimumCapturePlaneBuffers(min_dec_capture_buffers); ，
so I wonder why does the decoder need so many capture buffers? How is it calculated? Is it based on B frame number or DPB?
I want to reduce memory，can you give me some advice?
Thanks

2

Hi,
It should be specific to the h264 stream. Could you check what buffer number is for sample_outdoor_car_1080p_10fps.h264?

3

Hi DaneLLL,

The buffer number is 9 for sample_outdoor_car_1080p_10fps.h264.

5

Hi,
Please check the stream though JM decoder: Karsten Suehring

test.h264 has the information in SPS:

@432   SPS: log2_max_frame_num_minus4                          0001011 ( 10) 
@439   SPS: pic_order_cnt_type                                       1 (  0) 
@440   SPS: log2_max_pic_order_cnt_lsb_minus4                    00101 (  4) 
@445   SPS: num_ref_frames                                         010 (  1)

SPS in sample_outdoor_car_1080p_10fps.h264 is

@32    SPS: log2_max_frame_num_minus4                                1 (  0) 
@33    SPS: pic_order_cnt_type                                       1 (  0) 
@34    SPS: log2_max_pic_order_cnt_lsb_minus4                      011 (  2) 
@37    SPS: num_ref_frames                                       00101 (  4)

The buffer number is decided by the codec data. It is specific to the stream.

6

Hi DaneLLL,

Thank you.

7

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