raspberrypi
[BUG] rpicam-vid - cannot get bitrate higher than 3m using h264 codec
Describe the bug
When I use rpicam-vid with codec h264 and bitrate e.g. 20m -b 20000000, the bitrate of the final file is less than 3m. I tested with bitrates 5m, and 10m. Using libav + libx264 everything is fine.
Bug report
camera-bug-report -o bug.txt -c "rpicam-vid -n --width 1920 --height 1080 --framerate 10 --frames 100 --codec h264 -b 20000000 -o 20M.h264"
For example,
I use Raspberry Pi Zero 2 W and Raspberry Pi Camera Module 3. Try to save 10 seconds of video the file with a bitrate of 20m (quick calculation, 20m bitrate / 8 * 10 seconds, a file size will be ~25MB)
rpicam-vid -n --width 1920 --height 1080 --framerate 10 --frames 100 --codec h264 -b 20000000 -o 20M.h264
The final file size is below 3MB not as expected 25MB. I used ffmpeg -i 20M.h264 -c copy 20M.h264.mp4 to make mp4 and ffprobe -i 20M.h264.mp4 to see a bitrate. Is 2.4m instead of 20m!
When libav + libx264 is used, everything is fine (quality is better)
rpicam-vid -n --width 1920 --height 1080 --framerate 10 --frames 100 --codec libav --libav-video-codec libx264 --libav-video-codec-opts "preset=ultrafast" -b 20000000 -o 20M.mp4
[10:44:32.623513499] [2752] INFO Camera camera_manager.cpp:313 libcamera v0.3.0+65-6ddd79b5
[10:44:32.826678772] [2755] WARN RPiSdn sdn.cpp:40 Using legacy SDN tuning - please consider moving SDN inside rpi.denoise
[10:44:32.832154835] [2755] INFO RPI vc4.cpp:446 Registered camera /base/soc/i2c0mux/i2c@1/imx708@1a to Unicam device /dev/media3 and ISP device /dev/media0
[10:44:32.832293846] [2755] INFO RPI pipeline_base.cpp:1104 Using configuration file '/usr/share/libcamera/pipeline/rpi/vc4/rpi_apps.yaml'
Mode selection for 1920:1080:12:P(10)
SRGGB10_CSI2P,1536x864/120.135 - Score: 2200
SRGGB10_CSI2P,2304x1296/56.0255 - Score: 1150
SRGGB10_CSI2P,4608x2592/14.3536 - Score: 2050
[10:44:32.847986928] [2752] INFO Camera camera.cpp:1183 configuring streams: (0) 1920x1080-YUV420 (1) 2304x1296-SBGGR10_CSI2P
[10:44:32.849155422] [2755] INFO RPI vc4.cpp:621 Sensor: /base/soc/i2c0mux/i2c@1/imx708@1a - Selected sensor format: 2304x1296-SBGGR10_1X10 - Selected unicam format: 2304x1296-pBAA
[libx264 @ 0x55ae155890] using cpu capabilities: ARMv8 NEON
[libx264 @ 0x55ae155890] profile Main, level 4.1, 4:2:0, 8-bit
[libx264 @ 0x55ae155890] 264 - core 164 r3095 baee400 - H.264/MPEG-4 AVC codec - Copyleft 2003-2022 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0x1 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=0 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 slices=1 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=1 b_pyramid=0 b_adapt=0 b_bias=0 direct=1 weightb=0 open_gop=0 weightp=0 keyint=10 keyint_min=1 scenecut=0 intra_refresh=0 rc=abr mbtree=0 bitrate=20000 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 pb_ratio=1.30 aq=0
Output #0, mp4, to '20M.mp4':
Stream #0:0: Video: h264, yuv420p(tv, bt709), 1920x1080, q=2-31, 20000 kb/s, 10 fps, 10 tbr, 1000k tbn
[libx264 @ 0x55ae155890] frame I:10 Avg QP: 6.40 size:541195
[libx264 @ 0x55ae155890] frame P:50 Avg QP: 9.22 size:290336
[libx264 @ 0x55ae155890] frame B:40 Avg QP:11.55 size:175845
[libx264 @ 0x55ae155890] consecutive B-frames: 20.0% 80.0%
[libx264 @ 0x55ae155890] mb I I16..4: 100.0% 0.0% 0.0%
[libx264 @ 0x55ae155890] mb P I16..4: 16.5% 0.0% 19.0% P16..4: 61.2% 0.0% 0.0% 0.0% 0.0% skip: 3.3%
[libx264 @ 0x55ae155890] mb B I16..4: 7.5% 0.0% 2.1% B16..8: 34.9% 0.0% 0.0% direct:48.2% skip: 7.3% L0:40.1% L1:37.5% BI:22.3%
[libx264 @ 0x55ae155890] final ratefactor: 13.77
[libx264 @ 0x55ae155890] coded y,uvDC,uvAC intra: 93.9% 86.0% 79.0% inter: 76.9% 37.3% 10.5%
[libx264 @ 0x55ae155890] i16 v,h,dc,p: 15% 17% 35% 32%
[libx264 @ 0x55ae155890] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 18% 15% 34% 4% 8% 4% 5% 4% 7%
[libx264 @ 0x55ae155890] i8c dc,h,v,p: 40% 26% 18% 16%
[libx264 @ 0x55ae155890] kb/s:21571.53
Log report bitrate is 21571.53 File size is 25MB.
Using h264 and bitrate 1m generate a result file of ~1MB. It means I can change a bitrate, but above 3m is lowered to 3m.
rpicam-vid -n --width 1920 --height 1080 --framerate 10 --frames 100 --codec h264 -b 1000000 -o 1M.h264
I have not seen any bitrate limitation of h264 codec using rpicam-vid in documentation.
The final encoded bitrate might be scene dependent. Can you describe what you are recording?
