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• Ffmpeg configuration to stream the frames of my webcam

  6 juillet 2023, par Ridweng

  I'm trying to build a server in NodeJs to stream in RTSP my webcam using Angular to retrieve the frames and connecting using websockets. The server side is using "express-ws" module to create the Websocket.

  


  I was successfull in sending the frames from the webcam to the server in base64, the server is receiving these messages from a function on interval of (1000 / 30)ms.

  


  The issue relies on the implementation of my Ffmpeg child process. I retrieve the message and convert it into a buffer to then write this in the function of Ffmpeg.

  


  My current implementation is this one :

  


  const { spawn } = require('child_process');
exports.stream =  (ws ,req) => {
    try{
        const mess = `connection from: ${req._remoteAddress} at ${req._startTime}.`
        const initialMess =`Started ${mess}`
        ws.uuid = uuidv4()
        console.log(initialMess)

        ws.on('message', function incoming(message) {
            message = JSON.parse(message)
            console.log(`Res: ${message.width} x ${message.height}`);
            const ffmpeg = spawn('ffmpeg', [
                '-f', 'rawvideo',
                '-pixel_format', 'rgb24',
                '-video_size', `${message.width}x${message.height}`,
                '-framerate', `${message.framerate}`,
                '-i', '-',
                '-codec:v', 'libx264',
                '-preset', 'ultrafast',
                '-tune', 'zerolatency',
                '-f', 'rtsp',
                'rtsp://127.0.0.1:554/rtsp/stream',
            ]);
            const base64Data = message.video;
            const videoData = Buffer.from(base64Data, 'base64');

            ffmpeg.stdin.write(videoData);
            ffmpeg.stdin.end();
            
            ffmpeg.stderr.on('data', (data) => {
                console.error(`FFmpeg : ${data}`);
                });

            ffmpeg.on('exit', (code, signal) => {
                if (dev) console.log(`FFmpeg process exited with code ${code} and signal ${signal}`);
        
                // Close the WebSocket connection
                ws.close();
                });
        });
        ws.on('close', () => {
            const finalMess = `Stopped ${mess}`
            rem(ws.uuid)
            console.log(finalMess)
        })
    }catch(err){
        console.log(err)
    }
}


  


  In terms of the message received, this is the Angular side sending the message :

  


  const imageData = this.canvas.toDataURL('image/jpeg');
socket.send(JSON.stringify({video: imageData, width: this.canvas.width, height: this.canvas.height, framerate: interval }));


  


  The interval variable is the divisor of the interval that is triggering the function (in this case 30).

  


  I'm currently receiving the error message from Ffmpeg :

  


  ffmpeg version 6.0 Copyright (c) 2000-2023 the FFmpeg developers
  built with Apple clang version 14.0.3 (clang-1403.0.22.14.1)

FFmpeg :   configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.0 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
  libavutil      58.  2.100 / 58.  2.100
  libavcodec     60.  3.100 / 60.  3.100
  libavformat    60.  3.100 / 60.  3.100
  libavdevice    60.  1.100 / 60.  1.100
  libavfilter     9.  3.100 /  9.  3.100
  libswscale      7.  1.100 /  7.  1.100
  libswresample   4. 10.100 /  4. 10.100
  libpostproc    57.  1.100 / 57.  1.100

FFmpeg : [rawvideo @ 0x150005ff0] Packet corrupt (stream = 0, dts = 0).

FFmpeg : Input #0, rawvideo, from 'fd:':
  Duration: N/A, start: 0.000000, bitrate: 221184 kb/s
  Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 640x480, 221184 kb/s, 30 tbr, 30 tbn

FFmpeg : Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))

FFmpeg : fd:: corrupt input packet in stream 0
[rawvideo @ 0x14ef24290] Invalid buffer size, packet size 76343 < expected frame_size 921600

FFmpeg : Error while decoding stream #0:0: Invalid argument

FFmpeg : [libx264 @ 0x14ef25a20] using cpu capabilities: ARMv8 NEON

FFmpeg : [libx264 @ 0x14ef25a20] profile High 4:4:4 Predictive, level 3.0, 4:4:4, 8-bit

FFmpeg : [libx264 @ 0x14ef25a20] 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=0:0 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=6 threads=7 lookahead_threads=7 sliced_threads=1 slices=7 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=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0

FFmpeg : [tcp @ 0x1500078a0] Connection to tcp://127.0.0.1:554?timeout=0 failed: Connection refused
[out#0/rtsp @ 0x14ef24b00] Could not write header (incorrect codec parameters ?): Connection refused

FFmpeg : [vost#0:0/libx264 @ 0x14ef256d0] Error initializing output stream: 

FFmpeg : Conversion failed!

FFmpeg process exited with code 1 and signal null


  


  This is the reason I believe the issue relies on the configuration of Ffmpeg and how to set it for this case. It would be great to being able to play this RTSP link in my VLC to conclude it as successfull.

  


  I would apreciate any suggestions or guidence.
Thanks in advance.

  


• Approaches To Modifying Game Resource Files

  16 août 2016, par Multimedia Mike — Game Hacking

  I have been assisting The Translator in the translation of another mid-1990s adventure game. This one isn’t quite as multimedia-heavy as the last title, and the challenges are a bit different. I wanted to compose this post in order to describe my thought process and mental model in approaching this problem. Hopefully, this will help some others understand my approach since what I’m doing here often appears as magic to some of my correspondents.

  High Level Model
  At the highest level, it is valuable to understand the code and the data at play. The code is the game’s engine and the data refers to the collection of resources that comprise the game’s graphics, sound, text, and other assets.

  
  
  Simplistic high-level game engine model
  

  Ideally, we want to change the data in such a way that the original game engine adopts it as its own because it has the same format as the original data. It is very undesirable to have to modify the binary engine executable in any way.

  Modifying The Game Data Directly
  How to modify the data ? If we modify the text strings for the sake of language translation, one approach might be to search for strings within the game data files and change them directly. This model assumes that the text strings are stored in a plain, uncompressed format. Some games might store these strings in a text format which can be easily edited with any text editor. Other games will store them as binary data.
  

  In the latter situation, a game hacker can scan through data files with utilities like Unix ‘strings’ to find the resources with the desired strings. Then, use a hex editor to edit the strings directly. For example, change “Original String”…

  0098F800   00 00 00 00  00 00 00 4F  72 69 67 69  6E 61 6C 20  .......Original 
  0098F810   53 74 72 69  6E 67 00 00  00 00 00 00  00 00 00 00  String..........
  

  …to “Short String” and pad the difference in string lengths using spaces (0x20) :

  0098F800   00 00 00 00  00 00 00 53  68 6F 72 74  20 53 74 72  .......Short Str
  0098F810   69 6E 67 20  20 20 00 00  00 00 00 00  00 00 00 00  ing   ..........
  

  This has some obvious problems. First, translated strings need to be of equal our smaller length compared to the original. What if we want to encode “Much Longer String” ?

  0098F800   00 00 00 00  00 00 00 4D  75 63 68 20  4C 6F 6E 67  .......Much Long
  0098F810   65 72 20 53  74 72 00 00  00 00 00 00  00 00 00 00  er Str..........
  

  It won’t fit. The second problem pertains to character set limitations. If the font in use was only designed for ASCII, it’s going to be inadequate for expressing nearly any other language.

  So a better approach is needed.

  Understanding The Data Structures
  An alternative to the approach outlined above is to understand the game’s resources so they can be modified at a deeper level. Here’s a model to motivate this investigation :

  
  
  Model of the game resource archive format
  

  This is a very common layout for such formats : there is a file header, a sequence of resource blocks, and a trailing index which describes the locations and types of the foregoing blocks.

  What use is understanding the data structures ? In doing so, it becomes possible to write new utilities that disassemble the data into individual pieces, modify the necessary pieces, and then reassemble them into a form that the original game engine likes.

  It’s important to take a careful, experimental approach to this since mistakes can be ruthlessly difficult to debug (unless you relish the thought of debugging the control flow through an opaque DOS executable). Thus, the very first goal in all of this is to create a program that can disassemble and reassemble the resource, thus creating an identical resource file. This diagram illustrates this complex initial process :

  
  
  Rewriting the game resource file
  

  So, yeah, this is one of the most complicated “copy file” operations that I can possibly code. But it forms an important basis, since the next step is to carefully replace one piece at a time.

  
  
  Modifying a specific game resource
  

  This diagram shows a simplistic model of a resource block that contains a series of message strings. The header contains pointers to each of the strings within the block. Instead of copying this particular resource block directly to the new file, a proposed modification utility will intercept it and rewrite the entire thing, writing new strings of arbitrary length and creating an adjusted header which will correctly point to the start of each new string. Thus, translated strings can be longer than the original strings.

  Further Work
  Exploiting this same approach, we can intercept and modify other game resources including fonts, images, and anything else that might need to be translated. I will explore specific examples in a later blog post.

  Followup

  • Translating Return to Ringworld, in which I apply the ideas expressed in this post.

• compiling ffmpeg for Mac OSX High Sierra 10.13

  29 juillet 2021, par Martin

  Hello I made an electron app that uses ffmpeg to combine audio and renders video, it works fine on windows, linux, and modern mac osx computers, but a user has reported to me that on an older version of mac osx such as High Sierra 10.13, the way that I have setup ffmpeg does not work.

  


  I have a virtual machine with High Sierra v10.13 where I install RenderTune-mac.dmg from my RenderTune releases page, then I download 2 audio files and the image from this link. I open RenderTune, and try render a video. My command to combine the audio files into a single mp3 works fine, but when I try to combine that mp3 with the image file, the ffmpeg build I have packaged with my electron app fails with this error :

  


  Command was killed with SIGABRT (Aborted): /Applications/RenderTune.app/Contents/Resources/ffmpeg -loop 1 -framerate 2 -i /Users/martin/Downloads/R-3777978-1344032418-8379.jpeg.jpg -i /Users/martin/Downloads/output-871140.mp3 -y -acodec copy -b:a 320k -vcodec libx264 -b:v 8000k -maxrate 8000k -minrate 8000k -bufsize 3M -filter:v scale=w=1920:h=1954 -preset medium -tune stillimage -crf 18 -pix_fmt yuv420p -shortest /Users/martin/Downloads/concatVideo-871140.mp4
ffmpeg version git-2021-03-24-13335df Copyright (c) 2000-2021 the FFmpeg developers
  built with Apple LLVM version 10.0.1 (clang-1001.0.46.4)
  configuration: --pkgconfigdir=/Users/martinbarker/Documents/projects/rendertune-0.5.0/workspace/lib/pkgconfig --prefix=/Users/martinbarker/Documents/projects/rendertune-0.5.0/workspace --pkg-config-flags=--static --extra-cflags='-I/Users/martinbarker/Documents/projects/rendertune-0.5.0/workspace/include -mmacosx-version-min=10.10' --extra-ldflags='-L/Users/martinbarker/Documents/projects/rendertune-0.5.0/workspace/lib -mmacosx-version-min=10.10' --extra-libs='-lpthread -lm' --enable-static --disable-securetransport --disable-debug --disable-shared --disable-ffplay --disable-lzma --disable-doc --enable-version3 --enable-pthreads --enable-runtime-cpudetect --enable-avfilter --enable-filters --disable-libxcb --enable-gpl --enable-nonfree --disable-libass --enable-libfdk-aac --enable-libmp3lame --enable-libx264
  libavutil      56. 66.100 / 56. 66.100
  libavcodec     58.128.100 / 58.128.100
  libavformat    58. 69.100 / 58. 69.100
  libavdevice    58. 12.100 / 58. 12.100
  libavfilter     7.107.100 /  7.107.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Input #0, image2, from '/Users/martin/Downloads/R-3777978-1344032418-8379.jpeg.jpg':
  Duration: 00:00:00.50, start: 0.000000, bitrate: 1758 kb/s
  Stream #0:0: Video: mjpeg (Progressive), yuvj444p(pc, bt470bg/unknown/unknown), 590x600 [SAR 1:1 DAR 59:60], 2 fps, 2 tbr, 2 tbn, 2 tbc
Input #1, mp3, from '/Users/martin/Downloads/output-871140.mp3':
  Metadata:
    title           : My Little Grass Shack
    album           : Our Hawaii - A Collection Of Personal Favorites
    artist          : Society Of Seven
    track           : 11
    encoder         : Lavf58.69.100
  Duration: 00:06:25.59, start: 0.025057, bitrate: 320 kb/s
  Stream #1:0: Audio: mp3, 44100 Hz, stereo, fltp, 320 kb/s
    Metadata:
      encoder         : Lavc58.12
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
  Stream #1:0 -> #0:1 (copy)
Press [q] to stop, [?] for help
[swscaler @ 0x7fbad9167600] deprecated pixel format used, make sure you did set range correctly
[libx264 @ 0x7fbad9040400] using SAR=2681/2679
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /Applications/RenderTune.app/Contents/Resources/ffmpeg
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /Applications/RenderTune.app/Contents/Resources/ffmpeg
  Expected in: /usr/lib/libSystem.B.dylib

    at makeError (/Applications/Render…eca/lib/error.js:59)
    at handlePromise (/Applications/Render…/execa/index.js:114)
    at async file:/Applicat…js/newindex.js:1323


  


  These files will render fine on windows/linux and recent mac versions. In order to package ffmpeg in my electron app on mac computers I had to build a custom sandboxed version with no dynamically linked libraries. I have a .sh file that automatically downloads ffmpeg and builds it with all the necessary flags for mac computers.
https://github.com/MartinBarker/RenderTune/blob/master/buildffmpeg.sh
Inside this .sh file is where I compile ffmpeg using these flags :

  


  ./configure \
    --pkgconfigdir="$WORKSPACE/lib/pkgconfig" \
    --prefix=${WORKSPACE} \
    --pkg-config-flags="--static" \
    --extra-cflags="-I$WORKSPACE/include -mmacosx-version-min=${MACOS_MIN}" \
    --extra-ldflags="-L$WORKSPACE/lib -mmacosx-version-min=${MACOS_MIN}" \
    --extra-libs="-lpthread -lm" \
        --enable-static \
        --disable-securetransport \
        --disable-debug \
        --disable-shared \
        --disable-ffplay \
        --disable-lzma \
        --disable-doc \
        --enable-version3 \
        --enable-pthreads \
        --enable-runtime-cpudetect \
        --enable-avfilter \
        --enable-filters \
        --disable-libxcb \
        --enable-gpl \
        --enable-nonfree \
        --disable-libass \
        --enable-libfdk-aac \
        --enable-libmp3lame \
        --enable-libx264 


  


  If I try to run this script in my High Sierra VM, it fails with this message :

  


  Unknown option "-extra-libs=-lpthread"

  


  if I remove that flag it fails with a different message :

  


  Unknown option "--enable-static"

  


  I need this flag in order to release my electron app on the mac apple store, can anyone help me compile a static version of ffmpeg that works on old versions like High Sierra 10.13 as well as works on modern mac os systems ?