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• FFMPEG stereo track stops capturing at random times during a capture session

  26 mai 2022, par mrwassen

  I am currently working on building a workflow to capture and archive a large stash of family and friends PAL and NTSC VHS tapes. The hardware setup is as follows :

  


  

  • JVC HR-7860S VCR

  


  • s-video / RCA audio >

  


  • ADVC-3000 converter

  


  • SDI / BNC cable >

  


  • Blackmagic Decklink Mini Recorder 4K PCIe card

  


  • installed in a fairly hi-spec windows machine : AMD Ryzen 9 5900X 3.7 Ghz base 12 core, GEFORCE RTX 3060 12 gB, 32 gB ram

  


  


  The plan is to capture to lossless AVI, then drop into an NLE (Vegas Pro v.16) to do a minimal amount of cleanup / trimming, then render to a more compressed video format (TBD) for upload to AWS S3 accessible through a family website.

  


  The issue I am having is that when I run the capture using ffmpeg/directshow e.g. for a perfectly fine 90 min. PAL tape, at some random point of time during the capture one of the 2 stereo channels just stops capturing. This has happened with all of the tapes I have tested so far, and it happens at different times during the same video. I have examined the frames surrounding points in time when this happens, and it doesn't correlate to any transitions or jitter, but often just randomly in the middle of a perfectly smooth scene. Once the one channel stops capturing it never starts back up again during that capture session.

  


  The ADVC-3000 and the VCR are both showing both stereo channels playing normally throughout the capture. The windows machine running the capture hardly breaks a sweat at any time, and the transfer easily keeps up constantly showing a speed = 1x which I assume means nothing lagging. Also there are no video/audio sync issues at any point in time even towards the end of long tapes e.g. 90 mins.

  


  I am fairly new at ffmpeg, so I have spent extensive amounts of time reading up on forum posts and experimenting and have ended up with the following syntax :

  


  ffmpeg -y -f dshow -rtbufsize 2000M -i video="Blackmagic WDM Capture":audio="Blackmagic WDM Capture" -codec:v v210 -pix_fmt yuv422p -codec:a pcm_s16le -b:a 128k -t 02:00:00 -r 25 -threads 4 -maxrate 2500k -filter:a "volume=1.5" output_v210_audio.avi


  


  The capture runs without a single dropped frame, the only error I am getting when launching (and perhaps this is a smoking gun ?) is :

  


  


  "Non-monotonous DTS in output stream 0:1 ; previous : 0, current : -30 ;
changing to 1. This may result in incorrect timestamps in the output
file."

  


  


  I have tried to troubleshoot this in the hopes that it is tied to my issue but so far without luck.

  


  Hoping somebody can help correct or modify my command line or perhaps other ideas to help resolve the issue.

  


• FFmpeg throwing error during video render process using Remotion

  31 mai 2022, par Vince

  I'm using a tool called Remotion, which allows you to create videos using javascript (node & react). I have the server-side rendering process working, unless I try to include an mp3. Per their docs, I have my audio imported like this :

  


  import goodtimes from &#x27;../../music/GoodTimes.mp3&#x27;;&#xA;&#xA;...&#xA;&#xA;<audio src="{goodtimes}"></audio>&#xA;

  


  I'm currently trying to troubleshoot this using the CLI, because the error messaging is better. The command runs, and seems to generate the full video – 2400 out of 2400 frames. But then it fails with this output :

  


  (2/3) [====================] Rendered frames (6x) 176540ms&#xA;    &#x2B; [====================] Downloading http://localhost:3000/1ba90857580e6291.mp3&#xA;(3/3) [====================] Encoding video 2400/2400&#xA;An error occurred:&#xA;Error: Command failed with exit code 1: ffprobe -v error -show_entries stream=channels:format=duration -of default=nw=1 /var/folders/6n/_nfb38t53dgdj092_pcnqqmw0000gn/T/remotion-assets-dir2jc2oppruh/7744374580215663.mp3&#xA;[mp3 @ 0x7fa78152ec40] Failed to read frame size: Could not seek to 5244.&#xA;/var/folders/6n/_nfb38t53dgdj092_pcnqqmw0000gn/T/remotion-assets-dir2jc2oppruh/7744374580215663.mp3: Invalid argument&#xA;    at makeError (/Users/voverson/clm-video/server/node_modules/execa/lib/error.js:60:11)&#xA;    at handlePromise (/Users/voverson/clm-video/server/node_modules/execa/index.js:118:26)&#xA;    at runMicrotasks (<anonymous>)&#xA;    at processTicksAndRejections (internal/process/task_queues.js:93:5)&#xA;    at async getAudioChannelsAndDuration (/Users/voverson/clm-video/server/node_modules/@remotion/renderer/dist/assets/get-audio-channels.js:17:18)&#xA;    at async preprocessAudioTrackUnlimited (/Users/voverson/clm-video/server/node_modules/@remotion/renderer/dist/preprocess-audio-track.js:14:36)&#xA;</anonymous>

  


  I'm hoping some ffmpeg experts might recognize this error and have some idea what might be causing it.

  


• When I was try to use ffmpeg to convert video file extension, SharedArrayBuffer has troubles

  26 mai 2022, par DAN

  I want to convert video extension to .mp4 by using ffmpeg.

  


  At first, I wrote code like this.

  


  import{ createFFmpeg, fetchFile, } from '@ffmpeg/ffmpeg'

export default {
    setup() {
        const ffmpeg = createFFmpeg({ log: true, })
        const previewVideo = async (event) => {
            const file = event.target.files[0]

            if (file.size > 1024*1024*200) {
                alert("100MB 이하의 동영상만 등록할 수 있습니다.\n\n" + "현재 파일 용량" + (Math.round(file.size / (1024 * 1024))) + "MB")    
            } else {
                const previewVideo = document.getElementById("previewVideo")
                console.log('start')
                await ffmpeg.load()
                console.log('start transcoding')
                ffmpeg.FS('writeFile', 'test.mov', await fetchFile(file))
                await ffmpeg.run('-i', 'test.mov', 'test.mp4')
                console.log('complete transcoding')
                const data = ffmpeg.FS('readFile', 'test.mp4')
                const videoUrl = URL.createObjectURL(new Blob([data.buffer], { type: 'video/mp4'}))
                previewVideo.setAttribute("src", videoUrl)
                previewVideo.play()
            }
        }
    }
}


  


  But, when I inputed video file, below error occurred.

  


  Uncaught (in promise) ReferenceError: SharedArrayBuffer is not defined
    at 459bf020-690b-4964-b875-8028d2bcaf81:22:175
    at Object.load (createFFmpeg.js:64:20)
    at async Proxy.previewVideo (PostModal.vue:99:17)


  


  PostModal.vue:99:17 = await ffmpeg.load()

  


  So, I searched in google, finally I found one solution. And added below code in index.html body's bottom

  


  <code class="echappe-js">&lt;script&gt;&amp;#xA;  if (!crossOriginIsolated) SharedArrayBuffer = ArrayBuffer&amp;#xA;&lt;/script&gt;&#xA;

  


  And I could resolve that error !! However, another error occurred like below.

  


  Uncaught (in promise) Error: bad memory
    at 7d608d39-864a-4c63-930a-5ec5065337fe:23:1
    at Object.load (createFFmpeg.js:64:20)
    at async Proxy.previewVideo (PostModal.vue:99:17)


  


  I searched again. And then I found some people recommend to use coi-serviceworker.js
I added below code in index.html body's

  


  <code class="echappe-js">&lt;script src='http://stackoverflow.com/feeds/tag/coi-serviceworker.js'&gt;&lt;/script&gt;&#xA;

  


  And added file coi-serviceworker.js in my repo
file github link

  


  However, another two errors were occurred again...

  


  An SSL certificate error occurred when fetching the script.

COOP/COEP Service Worker failed to register: DOMException: Failed to register a ServiceWorker for scope ('https://localhost:3000/') with script ('https://localhost:3000/coi-serviceworker.js'): An SSL certificate error occurred when fetching the script.


  


  some solution recommended change Allow invalid certificates for resources loaded from localhost. to enable in chrome ://flags/#allow-insecure-localhost

  


  But, still occurred same error. I'm stuck here since I didn't find another solution. Could you have any another solution ?