Question / Help Raspberry Pi 4 DIY streaming backpack issues

[Berri]

So speedify created a blog post and youtube video about making an IRL streaming backpack using the Elgato Cam Link 4k, Raspberry Pi 4, and ffmpeg.

They gave pretty detailed instructions, and included downloads to prebuilt scripts/commands to get it all running once put together.
Blog post:
https://speedify.com/blog/how-to/build-irl-streaming-backpack-complete-guide/
ffmpeg command from post:

ffmpeg_command = “/home/pi/bin/ffmpeg -nostdin -re -f v4l2 -s ‘1280×720’ -framerate 24 -i /dev/video0 -f alsa -ac 2 -i hw:CARD=Link,DEV=0 -vcodec libx264 -framerate 24 -rtbufsize 1500k -s 1280×720 -preset ultrafast -pix_fmt yuv420p -crf 17 -force_key_frames ‘expr:gte(t,n_forced*2)’ -minrate 850k -maxrate 1000k -b:v 1000k -bufsize 1000k -acodec libmp3lame -rtbufsize 1500k -b 96k -ar 44100 -f flv – | ffmpeg -f flv -i – -c copy -f flv -drop_pkts_on_overflow 1 -attempt_recovery 1 -recovery_wait_time 1 rtmp://live.twitch.tv/app/live_” + streamKey + “‘\n”

(I replaced '-i hw:card=link,dev=0' in that command with '-i hw:2,0' as the original was giving me different errors and this seems to be working better)

Github Resources + Instructions:
https://github.com/speedify/rpi-streaming-experiment

I'm using all the exact same hardware as outlined in the post, and have gotten everything installed correctly as far as I can tell.
But when I go to run the ffmpeg command, it seems like nothing actually gets sent over to twitch correctly.

The log after trying to run it looks like this.
If anybody has any insight as to what may be going wrong, it would be greatly appreciated.

Starting ffmpeg
ffmpeg version N-95970-gd5274f8 Copyright (c) 2000-2019 the FFmpeg developers
built with gcc 8 (Raspbian 8.3.0-6+rpi1)
configuration: --prefix=/home/pi/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/pi/ffmpeg_build/include --extra-ldflags=-L/home/pi/ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/home/pi/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
libavutil 56. 36.101 / 56. 36.101
libavcodec 58. 64.101 / 58. 64.101
ffmpeg version N-95970-gd5274f8 libavformat 58. 35.101 / 58. 35.101
Copyright (c) 2000-2019 the FFmpeg developers libavdevice 58. 9.101 / 58. 9.101

libavfilter 7. 67.100 / 7. 67.100
built with gcc 8 (Raspbian 8.3.0-6+rpi1)
libswscale 5. 6.100 / 5. 6.100
configuration: --prefix=/home/pi/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/pi/ffmpeg_build/include --extra-ldflags=-L/home/pi/ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/home/pi/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
libavutil 56. 36.101 / 56. 36.101
libavcodec 58. 64.101 / 58. 64.101
libavformat 58. 35.101 / 58. 35.101
libavdevice 58. 9.101 / 58. 9.101
libavfilter 7. 67.100 / 7. 67.100
libswscale 5. 6.100 / 5. 6.100
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
[video4linux2,v4l2 @ 0x2aac5e0] The V4L2 driver changed the video from 1280x720 to 1920x1080
[video4linux2,v4l2 @ 0x2aac5e0] The driver changed the time per frame from 1/24 to 117/7013
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
Input #0, video4linux2,v4l2, from '/dev/video0':
Duration: N/A, start: 4683.201589, bitrate: 1491503 kb/s
Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 1920x1080, 1491503 kb/s, 59.94 fps, 59.94 tbr, 1000k tbn, 1000k tbc
Guessed Channel Layout for Input Stream #1.0 : stereo
Input #1, alsa, from 'hw:2,0':
Duration: N/A, start: 1576099663.557438, bitrate: 1536 kb/s
Stream #1:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
Please use -b:a or -b:v, -b is ambiguous
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (pcm_s16le (native) -> mp3 (libmp3lame))
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
Last message repeated 9 times
[video4linux2,v4l2 @ 0x2aac5e0] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
Last message repeated 28 times
frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
Last message repeated 29 times
frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
Last message repeated 29 times
frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
Last message repeated 29 times
frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
Last message repeated 29 times
frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
Last message repeated 29 times
frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
[video4linux2,v4l2 @ 0x2aac5e0] Dequeued v4l2 buffer contains 4147200 bytes, but 3110400 were expected. Flags: 0x00012001.
terminated script
pipe:: could not find codec parameters
Exiting normally, received signal 15.
Last message repeated 15 times
[alsa @ 0x2aaf2c0] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
Finishing stream 0:0 without any data written to it.
[libx264 @ 0x2abee40] using cpu capabilities: ARMv6 NEON
[libx264 @ 0x2abee40] profile Constrained Baseline, level 3.2, 4:2:0, 8-bit
[libx264 @ 0x2abee40] 264 - core 158 - H.264/MPEG-4 AVC codec - Copyleft 2003-2019 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc_lookahead=0 rc=crf mbtree=0 crf=17.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=1000 vbv_bufsize=1000 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=0
Finishing stream 0:1 without any data written to it.
Output #0, flv, to 'pipe:':
Metadata:
encoder : Lavf58.35.101
Stream #0:0: Video: h264 (libx264) ([7][0][0][0] / 0x0007), yuv420p, 1280x720, q=-1--1, 96 kb/s, 59.94 fps, 1k tbn, 59.94 tbc
Metadata:
encoder : Lavc58.64.101 libx264
Side data:
cpb: bitrate max/min/avg: 1000000/0/96000 buffer size: 1000000 vbv_delay: N/A
Stream #0:1: Audio: mp3 (libmp3lame) ([2][0][0][0] / 0x0002), 44100 Hz, stereo, s16p
Metadata:
encoder : Lavc58.64.101 libmp3lame
[flv @ 0x2abda90] Failed to update header with correct duration.
[flv @ 0x2abda90] Failed to update header with correct filesize.
Error writing trailer of pipe:: Broken pipe
frame= 0 fps=0.0 q=0.0 Lsize= 0kB time=00:00:00.00 bitrate=N/A speed= 0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Exiting normally, received signal 15.

 

[Berri]

I realize this doesn't directly involve OBS, but I'm not having any luck looking for help elsewhere so far.
If anybody knows a better place to ask, that would also be much appreciated.

 

[NightWolfPack]

I haven't got to that point with my build but will for sure share what I can once I get there. This is also my first Pi project.

 

[matias_pl]

Do have in mind that they missed out on the one of the most important factors. Since the Pi is a rather low CPU performance device encoding the stream on the CPU itself makes not much sense. And that's why they struggle to get more than 24fps from a 720p stream.

However there's a pretty decent hardware encoder available (apart from really good hardware decoder) that they should have used, allowing to get up to 1080p30 H.264 streaming with hardly any hit on the CPU utilization. Or 60 fps at 720p. Have a look at v4l2m2m - my tests show it's able to do 32 fps 1080p with no overclocking (omx_h264 maxes out at 30 fps at the same resolution). There are rumors that you can get 50 fps with overclocking.

And basically there's no difference if you use Pi4 or Pi0 - they share the same codec block. If you don't need USB3.0 you can safely go with a less expensive and power consuming RPi - there are inexpensive HDMI-CSI2 modules available that you connect to the camera port. The audio through that HDMI interface is a somewhat grey matter, but hey - nothing stops you from using a simple USB sound card.

 

[matias_pl]

As for your original question - i see that you have both "-" and "–" chars in your ffmpeg line. The second char (dash) won't be interpreted as a hyphen thus with ffmpeg you will get a file named – with all the contents. Change it to a "minus" and you should be good to go. Blame WYSIWIG CMS text editors with autocorrect features :)