samiamlabs
commented
3 years ago I tried to create a minimal example to reproduce this without using aiortc and ended up with this:
import av
from av import Codec
import os
import fractions
DEFAULT_BITRATE = 1000000 # 1 Mbps
MAX_FRAME_RATE = 30
test_video = os.path.join(os.path.dirname(
os.path.realpath(__file__)), 'video.mp4')
container = av.open(test_video)
video_stream = next(s for s in container.streams if s.type == 'video')
codec = None
frame_count = 0
for packet in container.demux(video_stream):
for frame in packet.decode():
if codec is None:
codec = av.CodecContext.create("h264_v4l2m2m", "w")
codec.width = frame.width
codec.height = frame.height
codec.bit_rate = DEFAULT_BITRATE
codec.pix_fmt = "yuv420p"
codec.framerate = fractions.Fraction(MAX_FRAME_RATE, 1)
codec.time_base = fractions.Fraction(1, MAX_FRAME_RATE)
codec.options = {
"profile:v": "baseline",
"level": "31",
"tune": "zerolatency", # does nothing using h264_omx
}
print("frame count:", frame_count)
frame_count += 1
for package in codec.encode(frame):
pass
print('finished')This ran just fine on the Raspberry Pi 4. No segfault. Maybe I should figure out how to write the encoded video to a file, just to make sure it actually worked but I suspect it did.
I already verified that this works:
ffmpeg -i video.mp4 -c:v h264_v4l2m2m -b:v 8M -c:a copy test.mp4
Am I correct in assuming that this means the problem is probably in aiortc and not in PyAV?
In that case I should probably close this issue...
jlaine
github-actions[bot]
Pieter-Antonio
unitree-czk
Overview
Hi!
I'm trying to stream video with decent resolution and framerate over WebRTC (aiortc) with my Raspberry Pi 4. This pull request adding support for h264_omx seemed really promising at first: https://github.com/aiortc/aiortc/pull/488 Unfortunately, it seems that h264_omx is considered deprecated and won't be supported on arm64. (At the very least, I can't get it to work...)
I tried to just swap the codec name in the code related to the pull request to aiortc I mentioned above from "h264_omx" to "h264_v4l2m2m". The encoder context seems to be created without any exceptions (some warnings get printed though) but segfaults when trying to run
self.codec.encode(frame).Should it be possible to use the "h264_v4l2m2m" codec or is it simply not supported at this point?
Expected behavior
Well... I was hoping that h264_v4l2m2m would work as a drop-in replacement for h264_omx and allow me to stream video to remote control a robot using a Raspberry Pi 4.
Actual behavior
Hard to debug segfault which seems to happen outside the python code
Traceback:
Investigation
Python debugging in VSCode and GDB
Reproduction
Run the webcam.py example in aiortc (modified to select h264 using the approach from this issue: https://github.com/aiortc/aiortc/issues/502) on Ubuntu 20.04.2 LTS for arm64 on a Raspberry Pi 4. Also, change the codec name from "h264_omx" to "h264_v4l2m2m" in https://github.com/aiortc/aiortc/blob/main/src/aiortc/codecs/h264.py Got an error related to the "profile" option after that so changed it to "profile:v" based on https://video.stackexchange.com/questions/2634/how-do-i-specify-baseline-h264-profile-using-ffmbc
I used a source build of FFmpeg 4.4 to get rid of the green overlay issue in 4.2.4 that is distributed by apt on focal (explained more here: https://www.willusher.io/general/2020/11/15/hw-accel-encoding-rpi4) but I don't know if that is relevant for this issue.
I can provide a Dockerfile for building FFmpeg etc if someone wants it.
Versions
Research
I have done the following: