H264 encoder in P4 interprets bitrate as bytes per second instead of bits per second (AEGHB-1265)

[sjaramillo-yx]

Checklist

• Checked the issue tracker for similar issues to ensure this is not a duplicate
• Read the documentation to confirm the issue is not addressed there and your configuration is set correctly
• Tested with the latest version to ensure the issue hasn't been fixed

How often does this bug occurs?

always

Expected behavior

The expected behavior is that if I set a bitrate of 6000000, at 1080p@30FPS, I should get around 0.1bpp using the formula 1920 * 1080 * bpp * 30 = 6000000

Actual behavior (suspected bug)

Actual behavior is that the largest buffers that I get from the encoder are 196608 bytes in size, which correspond to 5909760 bytes per second (196608 * 8 / (1920 * 1080) = 0.76), so a bitrate of 47278080 bps (8 times the target of 6 Mbps).

Error logs or terminal output

Steps to reproduce the behavior

1. Configure bitrate using V4L2_CID_MPEG_VIDEO_BITRATE to 6000000
2. Begin streaming at 1080p@30FPS using the HW encoder of ESP32-P4
3. Cover the sensor to obtain the largest buffer possible (noisy image = higher bitrate)
4. Check dequeued buffer size using the bytes_used member of the buffer, will be around 196608 bytes

Project release version

latest

System architecture

Intel/AMD 64-bit (modern PC, older Mac)

Operating system

Linux

Operating system version

Debian 12

Shell

Bash

Additional context

No response