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• Express - FFMPEG : Serve transcoded video instead of static video file

  30 septembre 2020, par No stupid questions

  I am creating a website to host videos downloaded on my computer online. However, many of these videos are not in a web friendly format (like .mkv or .flv). It is not an option to convert these files on the disk and then serve them as static files, converting needs to be done live by the server. I want to transcode these videos with ffmpeg to a web friendly format like webm.

  


  So far, I have been able to somewhat successfully transcode a video and serve it :

  


  import express from 'express';
import cors from 'cors';
import ffmpeg from 'fluent-ffmpeg';

const app = express();

app.use(cors());
app.use(express.json());

app.use('/static/videos', globalPasswordMiddleware, (req, res) => {
    res.contentType('webm');
    const videoPath = path.join('C:/videos', decodeURIComponent(req.path));
    ffmpeg(videoPath)
        .format('webm')
        .on('end', function () {
            console.log('file has been converted succesfully');
        })
        .on('error', function (err) {
            console.log('an error happened: ' + err.message);
        })
        .pipe(res, { end: true });
});


  


  However, I am still encountering three different issues :

  


  Firstly, while this code seems to work for transcoding something like a flash video into webm, there are still a number of videos I cannot get to play. For example, a number of videos that play in Chrome will still not play in Firefox or a number of videos that play on my PC won't on my ancient iPad. Are there more arguments I need to be passing to ffmpeg to transcode the video in a way that it will work on a greater number or devices/browsers ?

  


  Second, there is no ability to seek on the video or see how much time remains. When viewing a transcoded video it behaves more like a livestream than if I were serving it as a static file. How can I fix this ?

  


  And finally third, the transcoding is massively slow. Running in production mode, video playback has to buffer for a few seconds every five or so seconds. I am aware transcoding video is an intense process but I believe given my computer's hardware (i9 9900K) and how much faster it is at transcoding videos on Plex that I should be able to transcode videos faster than this.

  


• Having issues with exporting video in FFMPEG [closed]

  3 avril 2024, par Jake

  I am developing an application that uses FFMPEG to take numerous videos and concatenate them into one file. The user has the ability to flip an individual video if they would like. From Landscape to portrait. The application works as planned and it produces one single file, with the orientation however the user set them.

  


  The problem is, when I take that file that FFMPEG generated and tray to convert or copy it using FFMPEG. It will create a video file of all of the video prior to the segment where the orientation has been flipped. The flipped video as well as all of the other videos after it, will not be in the video.

  


  Below are the parameters to export each individual video.

  


  parameters = "-y -i " + '"' + frames[0].VideoPath + '"' + " -filter_complex " + '"' + @"[0:v]trim=" + frames[0].TimeCode.TotalSeconds + @":" + frames[1].TimeCode.TotalSeconds +
            @", setpts=PTS-STARTPTS[trimedv0];[trimedv0]yadif," + orientation + @"setsar=1/1, eq=contrast=1:brightness=" + video.Brightness + @", drawtext=text=\'%{pts\:localtime\:" + ToUnixTimestamp(frames[0].FrameTime) +
            @"\:'" + CurrentDisplayDateFormat.DateOutputFormat + @"'}\'" + @":fontfile =\'Fonts/" + font.FirstOrDefault() + @"\':fontcolor=" + fontColor + ":x=" + DATEXOFF +
            ":y=" + DATEYOFF + " -th:fontsize=" + tempFont +
            @":box=1:boxcolor=" + boxColor + @"@" + opacity + @", drawtext=text=\'%{pts\:localtime\:" + ToUnixTimestamp(frames[0].FrameTime) + @"\:'" + CurrentDisplayDateFormat.TimeOutputFormat + @"'}\'" + @":fontfile =\'Fonts/" + font.FirstOrDefault() + @"\':fontcolor=" + fontColor +
            ":x=" + TIMEXOFF + ":y=" + TIMEYOFF +
            " -th:fontsize=" + tempFont + @":box=1:boxcolor=" + boxColor + @"@" + opacity + ", " + fadeString + " -sn " + mapVar + " -progress - -nostats -an -c:v libx264 -b:v " + video.BitRate + " -preset ultrafast -profile:v baseline -level 3.0 " +
            @"-pix_fmt yuv420p -f mpegts " + vidPath + @"\v" + outputFile.ToString() + ".MP4";


  


  Below are the parameters to concatenate all of the videos :

  


  string parameters = "-y -probesize 100M -analyzeduration 100M -i concat:" + '"' + concatString + '"' + @" -c:v copy " + '"' + ExportOptions.CompleteDestinationPath + '"';


  


  Any ideas of what is going on and hopefully a solution ?

  


• What video format will allow Android MediaPlayer.seekTo() to reliably provide frame-accurate scrubbing ?

  8 juillet 2015, par Tim Closs

  We have an iOS app that we are currently rebuilding for Android. The app relies on being able to scrub video with frame accuracy. We have 3D animations that are rendered out as single frames ; we build subsets of frames into lots of small (1-2 second) videos ; and the app provides the ability to scrub those videos and see each individual frame.

  The MP4 videos we initially created work fine on iOS. When we tried to get them working on Android (using the MediaPlayer class), we entered a world of pain ! What we need to do is find a video format that will play and allow frame-accurate scrubbing across all Android devices, using MediaPlayer.seekTo(). Initially we are targetting Android 3.0 and above, but we probably want to stretch back to 2.3.3 after our initial release. Here’s what I’ve discovered so far :

  (A) Android claims that H264 "baseline profile" should be supported everywhere : (URL). However, within that, there are dozens of other settings that may or may not be supported. Is there a more fine-grained list anywhere ? Currently we are converting to H264 within an MP4 container.

  (B) I haven’t yet seen an Android device that will accurately scrub H264 files without inserting keyframes ("intra frames"). iOS will happily take H264 files without keyframes and provide accurate scrubbing. It seems that, to allow accurate scrubbing, we need to insert a keyframe for every frame of the video (the relevant ffmpeg setting is "-g 1"). This significantly increases the file size.

  (C) However, inserting a keyframe for every frame results in a video that will not play at all on the Samsung Galaxy Note 3 (Snapdragon chipset I believe). Reducing the keyframes to every second frame or above seems to work (ffmpeg setting "-g 2").

  To summarise :
  MediaPlayer.seekTo() seems very dependent on the video format, and varies across devices. Is this the intention ? Is there a base level of behaviour that seekTo() is supposed to provide, regardless of format ?

  What video format that will allow frame-accurate scrubbing (using MediaPlayer.seekTo()) across all Android devices (at least for 3.0 and above ?)