Video codec memory bandwidth

Hello,

I am interested to understand the GDDR memory bandwidth consumed by my video transcoding application in RTX 4090.

the Nsight command line to capture memory transaction metircs only shows the metrics for CUDA kernels of post processing filters.
ncu --metrics group:memory__dram_table .\ffmpeg.exe -vsync 0 -c:v h264_cuvid -i bbb_sunflower_2160p_60fps_normal.mp4 -frames 60 -f null -
ConvertNV12BLtoNV12 (15, 540, 1)x(64, 2, 1), Context 1, Stream 7, Device 0, CC 8.9
Section: Command line profiler metrics
--------------------------------------------------- ------------ ------------
Metric Name Metric Unit Metric Value
--------------------------------------------------- ------------ ------------
dram__bytes_read.sum Mbyte 12.54
dram__bytes_read.sum.pct_of_peak_sustained_elapsed % 83.53
dram__bytes_read.sum.per_second Gbyte/second 817.87
dram__bytes_write.sum byte 0
dram__bytes_write.sum.pct_of_peak_sustained_elapsed % 0
dram__bytes_write.sum.per_second byte/second 0
dram__sectors_read.sum sector 391,760
dram__sectors_write.sum sector 0
--------------------------------------------------- ------------ ------------

Also, the nvidia-smi tool for DRAM metrics is showing no activity.

nvidia-smi.exe dmon --select=ucmt --gpm-metrics=1,2,3,10

gpu sm mem enc dec mclk pclk fb bar1 rxpci txpci gract smutil smocc dram

Idx % % % % MHz MHz MB MB MB/s MB/s GPM:% GPM:% GPM:% GPM:%

0      0      0      0      0    405    450    575      1     17      1          -         -         -         -
0      0      0      0      0    405    270    575      1     22     16          -         -         -         -
0     23      3      0     10  10251   2535   1283      1      3   5014          -         -         -         -
0     25      2      0    100  10251   2775   1283      1      8   5355          -         -         -         -
0     23      2      0    100  10251   2775   1283      1     21   5468          -         -         -         -
0     23      2      0    100  10251   2775   1283      1      5   5471          -         -         -         -
0     22      2      0    100  10251   2775   1283      1     10   5471          -         -         -         -
0     21      2      0    100  10251   2775   1283      1      5   5727          -         -         -         -
0     22      2      0    100  10251   2775   1283      1     12   5806          -         -         -         -
0     24      2      0    100  10251   2775   1283      1     12   5471          -         -         -         -
0     23      2      0    100  10251   2775   1283      1     11   5496          -         -         -         -
0     23      2      0    100  10251   2775   1283      1      6   6091          -         -         -         -
0     23      2      0    100  10251   2775   1283      1      7   5705          -         -         -         -
0     23      2      0    100  10251   2775   1283      1      7   5866          -         -         -         -

Can you please help on this ?
Thanks,
Raghav