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Stereo master soundtrack
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Simulating MPEG1/2 transmission over a noisy channel [on hold]
17 novembre 2015, par StepTNTThe question may sound out of scope here but this is my last resource.
I need to write a software that does :
- Get an uncompressed video from disk
- Compress it into MPEG-1 or MPEG-2 being able to change quantization matrix, GOP size and/or macroblock size for DCT/motion search
- Apply a repetition code to add redundancy
- Simulate transmission over a noisy channel with given error rate
- Reconstruct the original stream from the repetition code
- Decode the video and compare it with the original one by gathering stats like frame-by-frame difference, file size and stuff like that
This should by done by a nice GUI to show the input and output videos, alongside their frame difference.
Given what I need to do, I can write some requirements :
- An encoder which allows me to change some of the parameters (needed for point 2)
- A language that allows me to work at bit level (needed for points 3 and 5)
- A language that allows me to build a nice GUI using a designer (GUI is not the core of the project so I can’t afford wasting time by writing one)
So far my searches have led to mixed results that are not giving me enough resources to start.
My first find was this MATLAB project which implements MPEG and has some parameters that can be tweaked (like quantization matrix and GOP pattern for example).
The problem here is that I don’t know MATLAB at all, so I have no idea on how to link everything and build a GUI.So the next step was to move to JAVA, and I found a LOT of FFMPEG wrappers, but none seems to allow me to set the parameters that I need. My last try was with Xuggler but the Wiki is down and the documentation does not talk about what I need. Plus, JAVA doesn’t work at bit level so I’d have issues applying the repetition code.
Failing with JAVA led me to C# and DirectShowNet, but the documentation is quite lacking and I don’t know how to start because I didn’t find anything related to setting the parameters that I need using Filters.
The question now is : is there any language/framework/platform that allows me to do what I need without having to deal with pure C/C++ ?
I’d expect a lot of stuff on this matter since we’re talking about well known codecs, still I’m having a hard time finding what I need. -
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Transcode WEBM to RTMP
7 avril 2024, par Justin WhiteSummary


My goal is to take a webcam stream from the browser and feed it into a program called Restreamer that takes in an RTMP stream.


I've deduced that the browser Recording API produces Blobs that can be saved as WEBM.


In order to stream the WEBM content to Restreamer I am attempting to use FFmpeg. I've read that forcing FLV format is required but otherwise all of the arguments are Greek to me. I've been unable to find a comparable topic where someone has tried to go from WEBM to RTMP. I have found examples of going the other direction, but reversing the FFmpeg command proved unfruitful.


Saving to FLV works fine. Using the following command, I am able to transcode a WEBM file to FLV and play it on VLC :

ffmpeg -i ~/big-buck-bunny_trailer.webm -f flv out.flv


However, if instead of outputting to a file I pass it to RTMP I get the following output :

ffmpeg -i ~/Downloads/big-buck-bunny_trailer.webm -f flv "rtmp://example.com/live"


ffmpeg version 5.0.1 Copyright (c) 2000-2022 the FFmpeg developers
 built with gcc 12 (GCC)
 configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --docdir=/usr/share/doc/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' --extra-ldflags='-Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1 ' --extra-cflags=' -I/usr/include/rav1e' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --enable-chromaprint --disable-crystalhd --enable-fontconfig --enable-frei0r --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libaom --enable-libdav1d --enable-libass --enable-libbluray --enable-libbs2b --enable-libcdio --enable-libdrm --enable-libjack --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libilbc --enable-libmp3lame --enable-libmysofa --enable-nvenc --enable-openal --enable-opencl --enable-opengl --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librav1e --enable-librtmp --enable-librubberband --enable-libsmbclient --enable-version3 --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-version3 --enable-vapoursynth --enable-libvpx --enable-vulkan --enable-libglslang --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libxml2 --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lv2 --enable-avfilter --enable-libmodplug --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-lto --enable-libmfx --enable-runtime-cpudetect
 libavutil 57. 17.100 / 57. 17.100
 libavcodec 59. 18.100 / 59. 18.100
 libavformat 59. 16.100 / 59. 16.100
 libavdevice 59. 4.100 / 59. 4.100
 libavfilter 8. 24.100 / 8. 24.100
 libswscale 6. 4.100 / 6. 4.100
 libswresample 4. 3.100 / 4. 3.100
 libpostproc 56. 3.100 / 56. 3.100
Input #0, matroska,webm, from '/home/kyjus25/big-buck-bunny_trailer.webm':
 Metadata:
 encoder : http://sourceforge.net/projects/yamka
 creation_time : 2010-05-20T08:21:12.000000Z
 Duration: 00:00:32.48, start: 0.000000, bitrate: 533 kb/s
 Stream #0:0(eng): Video: vp8, yuv420p(progressive), 640x360, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 1k tbn (default)
 Stream #0:1(eng): Audio: vorbis, 44100 Hz, mono, fltp (default)
HandShake: client signature does not match!
Stream mapping:
 Stream #0:0 -> #0:0 (vp8 (native) -> flv1 (flv))
 Stream #0:1 -> #0:1 (vorbis (native) -> mp3 (libmp3lame))
Press [q] to stop, [?] for help
Output #0, flv, to 'rtmp://example.com/live':
 Metadata:
 encoder : Lavf59.16.100
 Stream #0:0(eng): Video: flv1 ([2][0][0][0] / 0x0002), yuv420p(tv, bt470bg/unknown/unknown, progressive), 640x360 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 1k tbn (default)
 Metadata:
 encoder : Lavc59.18.100 flv
 Side data:
 cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
 Stream #0:1(eng): Audio: mp3 ([2][0][0][0] / 0x0002), 44100 Hz, mono, fltp (default)
 Metadata:
 encoder : Lavc59.18.100 libmp3lame
WriteN, RTMP send error 32 (136 bytes)7kB time=00:00:00.39 bitrate= 136.7kbits/s speed=71.2x 
WriteN, RTMP send error 32 (35 bytes)
WriteN, RTMP send error 9 (42 bytes)
av_interleaved_write_frame(): Operation not permitted
 Last message repeated 1 times
[flv @ 0x55d0dd0af700] Failed to update header with correct duration.
[flv @ 0x55d0dd0af700] Failed to update header with correct filesize.
Error writing trailer of rtmp://example.com/live: Operation not permitted
frame= 53 fps=0.0 q=4.3 Lsize= 146kB time=00:00:02.45 bitrate= 486.8kbits/s speed=42.8x 
video:128kB audio:19kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Error closing file rtmp://example.com/live: Operation not permitted
Conversion failed!



There are several interesting rabbit holes to follow here, but after following all of them I've come up with nothing.


•
HandShake: client signature does not match!
:

More of a warning than an error, I assumed because I was going from "WEBM -> FLV" instead of the more traditional "MP4 -> FLV".

•
av_interleaved_write_frame(): Operation not permitted
:

I found several issues on this. One of them calling it a storage issue, the other calling it a file permissions issue. I have plenty of disk space and have tried setting the input file to 777 permissions. However, the examples I've found on it being a file permissions issue all deal with outputting to a file rather than to an an RTMP IP.

•
Failed to update header with correct duration
:

Advice I found was to add-flvflags no_duration_filesize
to the command, which does suppress both "Failed to update..." errors, but does not fix the over-arching issue.

What I've Tried


• Multi-format transcoding


MP4 to RTMP does work correctly :

ffmpeg -i ~/Downloads/big-buck-bunny_trailer.mp4 -f flv "rtmp://example.com/live"

Theoretically, I could stream the WEBM to a file, transcode that to an MP4 file, and then transcode that to FLV/RTMP. Sounds awful.

• Pay for a service (Wowza, Flashphoner, api.video, etc)


Unfortunately precisely what I am trying to avoid.


• WebRTC to RTMP ?


WebRTC seems to be a peer-to-peer connection and doesn't play nicely with a server/client scenario.


• WebRTC to other ingest formats


Restreamer also supports incoming streams of HLS, DASH, RTP, RTSP, RTMP, and SRT. However, these all seem to be examples of network sources that would be exposed via an IP URL. I am not sure that FFmpeg can do that.


• Utilizing ffmpeg-wasm instead of CLI


Available here, I thought that maybe by using a browser implementation I may get different results. But no. Not even an error to the console.


• Streaming from OBS


For the record, yes, I have tried streaming from OBS instead of going through FFmpeg and the Restreamer platform itself does work for normal use. I use it often.


Post Script


I've not been able to find any relevant solutions online. I am shocked that streaming from a browser webcam has not been solved 1000 times prior. This is related to a question made 7 years ago but it was not resolved and Flash is no longer an option.


Recommendations


• Adding
-c:v libx264 -flags:v +global_header -c:a aac -ac 2
:

ffmpeg version 5.0.1 Copyright (c) 2000-2022 the FFmpeg developers
 built with gcc 12 (GCC)
 configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --docdir=/usr/share/doc/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' --extra-ldflags='-Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1 ' --extra-cflags=' -I/usr/include/rav1e' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --enable-chromaprint --disable-crystalhd --enable-fontconfig --enable-frei0r --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libaom --enable-libdav1d --enable-libass --enable-libbluray --enable-libbs2b --enable-libcdio --enable-libdrm --enable-libjack --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libilbc --enable-libmp3lame --enable-libmysofa --enable-nvenc --enable-openal --enable-opencl --enable-opengl --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librav1e --enable-librtmp --enable-librubberband --enable-libsmbclient --enable-version3 --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-version3 --enable-vapoursynth --enable-libvpx --enable-vulkan --enable-libglslang --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libxml2 --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lv2 --enable-avfilter --enable-libmodplug --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-lto --enable-libmfx --enable-runtime-cpudetect
 libavutil 57. 17.100 / 57. 17.100
 libavcodec 59. 18.100 / 59. 18.100
 libavformat 59. 16.100 / 59. 16.100
 libavdevice 59. 4.100 / 59. 4.100
 libavfilter 8. 24.100 / 8. 24.100
 libswscale 6. 4.100 / 6. 4.100
 libswresample 4. 3.100 / 4. 3.100
 libpostproc 56. 3.100 / 56. 3.100
Input #0, matroska,webm, from '/home/kyjus25/big-buck-bunny_trailer.webm':
 Metadata:
 encoder : http://sourceforge.net/projects/yamka
 creation_time : 2010-05-20T08:21:12.000000Z
 Duration: 00:00:32.48, start: 0.000000, bitrate: 533 kb/s
 Stream #0:0(eng): Video: vp8, yuv420p(progressive), 640x360, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 1k tbn (default)
 Stream #0:1(eng): Audio: vorbis, 44100 Hz, mono, fltp (default)
HandShake: client signature does not match!
Stream mapping:
 Stream #0:0 -> #0:0 (vp8 (native) -> h264 (libx264))
 Stream #0:1 -> #0:1 (vorbis (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x561564271fc0] using SAR=1/1
[libx264 @ 0x561564271fc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x561564271fc0] profile High, level 3.0, 4:2:0, 8-bit
[libx264 @ 0x561564271fc0] 264 - core 163 r3060 5db6aa6 - H.264/MPEG-4 AVC codec - Copyleft 2003-2021 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=11 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, flv, to 'rtmp://example.com/live':
 Metadata:
 encoder : Lavf59.16.100
 Stream #0:0(eng): Video: h264 ([7][0][0][0] / 0x0007), yuv420p(tv, bt470bg/unknown/unknown, progressive), 640x360 [SAR 1:1 DAR 16:9], q=2-31, 25 fps, 1k tbn (default)
 Metadata:
 encoder : Lavc59.18.100 libx264
 Side data:
 cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
 Stream #0:1(eng): Audio: aac (LC) ([10][0][0][0] / 0x000A), 44100 Hz, stereo, fltp, 128 kb/s (default)
 Metadata:
 encoder : Lavc59.18.100 aac
Larger timestamp than 24-bit: 0xffffff77kB time=00:00:30.18 bitrate= 460.0kbits/s speed=19.7x 
[flv @ 0x56156425e440] Failed to update header with correct duration.
[flv @ 0x56156425e440] Failed to update header with correct filesize.
frame= 812 fps=475 q=-1.0 Lsize= 1901kB time=00:00:32.52 bitrate= 479.0kbits/s speed= 19x 
video:1354kB audio:508kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 2.123872%
[libx264 @ 0x561564271fc0] frame I:21 Avg QP:15.05 size: 8839
[libx264 @ 0x561564271fc0] frame P:293 Avg QP:20.78 size: 3087
[libx264 @ 0x561564271fc0] frame B:498 Avg QP:22.20 size: 593
[libx264 @ 0x561564271fc0] consecutive B-frames: 14.7% 7.6% 9.2% 68.5%
[libx264 @ 0x561564271fc0] mb I I16..4: 42.6% 41.9% 15.5%
[libx264 @ 0x561564271fc0] mb P I16..4: 4.0% 8.0% 0.9% P16..4: 22.7% 8.0% 4.0% 0.0% 0.0% skip:52.4%
[libx264 @ 0x561564271fc0] mb B I16..4: 1.4% 1.5% 0.2% B16..8: 12.0% 1.0% 0.2% direct: 3.3% skip:80.5% L0:44.1% L1:47.1% BI: 8.8%
[libx264 @ 0x561564271fc0] 8x8 transform intra:53.6% inter:57.0%
[libx264 @ 0x561564271fc0] coded y,uvDC,uvAC intra: 35.1% 37.7% 11.2% inter: 7.8% 9.5% 2.4%
[libx264 @ 0x561564271fc0] i16 v,h,dc,p: 56% 21% 14% 9%
[libx264 @ 0x561564271fc0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 32% 26% 21% 3% 3% 4% 4% 3% 4%
[libx264 @ 0x561564271fc0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 27% 21% 18% 4% 7% 7% 6% 5% 4%
[libx264 @ 0x561564271fc0] i8c dc,h,v,p: 62% 21% 15% 2%
[libx264 @ 0x561564271fc0] Weighted P-Frames: Y:20.8% UV:19.5%
[libx264 @ 0x561564271fc0] ref P L0: 70.3% 17.7% 9.0% 2.9% 0.0%
[libx264 @ 0x561564271fc0] ref B L0: 89.3% 8.9% 1.9%
[libx264 @ 0x561564271fc0] ref B L1: 96.4% 3.6%
[libx264 @ 0x561564271fc0] kb/s:341.30
[aac @ 0x561564223140] Qavg: 952.636



Seems to complete successfully, but does so rather quickly. Log outputs a new
Larger timestamp than 24-bit: 0xffffff77kB