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• Zlib vs. XZ on 2SF

  21 juillet 2012, par Multimedia Mike — General, psf, saltygme, xz, zlib

  I recently released my Game Music Appreciation website. It allows users to play an enormous range of video game music directly in their browsers. To do this, the site has to host the music. And since I’m a compression bore, I have to know how small I can practically make these music files. I already published the results of my effort to see if XZ could beat RAR (RAR won, but only slightly, and I still went with XZ for the project) on the corpus of Super Nintendo chiptune sets. Next is the corpus of Nintendo DS chiptunes.

  Repacking Nintendo DS 2SF
  The prevailing chiptune format for storing Nintendo DS songs is the .2sf format. This is a subtype of the Portable Sound Format (PSF). The designers had the foresight to build compression directly into the format. Much of payload data in a PSF file is compressed with zlib. Since I already incorporated Embedded XZ into the player project, I decided to try repacking the PSF payload data from zlib -> xz.

  In an effort to not corrupt standards too much, I changed the ’PSF’ file signature (seen in the first 3 bytes of a file) to ’psf’.

  Results
  There are about 900 Nintendo DS games currently represented in my website’s archive. Total size of the original PSF archive, payloads packed with zlib : 2.992 GB. Total size of the same archive with payloads packed as xz : 2.059 GB.

  Using xz vs. zlib saved me nearly a gigabyte of storage. That extra storage doesn’t really impact my hosting plan very much (I have 1/2 TB, which is why I’m so nonchalant about hosting the massive MPlayer Samples Archive). However, smaller individual files translates to a better user experience since the files are faster to download.

  Here is a pretty picture to illustrate the space savings :

  
  
  

  The blue occasionally appears to dip below the orange but the data indicates that xz is always more efficient than zlib. Here’s the raw data (comes in vanilla CSV flavor too).

  Interface Impact
  So the good news for the end user is that the songs are faster to load up front. The downside is that there can be a noticeable delay when changing tracks. Even though all songs are packaged into one file for download, and the entire file is downloaded before playback begins, each song is individually compressed. Thus, changing tracks triggers another decompression operation. I’m toying the possibility of some sort of background process that decompresses song (n+1) while playing song (n) in order to help compensate for this.

  I don’t like the idea of decompressing everything up front because A) it would take even longer to start playing ; and B) it would take a huge amount of memory.

  Corner Case
  There was at least one case in which I found zlib to be better than xz. It looks like zlib’s minimum block size is smaller than xz’s. I think I discovered xz to be unable to compress a few bytes to a block any smaller than about 60-64 bytes while zlib got it down into the teens. However, in those cases, it was more efficient to just leave the data uncompressed anyway.

• Remove parts of a video automagically without reencode ?

  21 août 2022, par Sam

  I'm looking for a way to remove automatically the opening and ending parts of a video (credits) without reencode.

  


  If you need an example, take Game of Thrones : I'd need a way to automatically remove the GoT opening (with the theme music) and the ending part (with the credits and the HBO logo part).

  


  FFmpeg can do that, but the cut has to be manual and happens only at keyframes... which isn't precise enough for me.

  


  I thought that maybe there is a tool that allows to scan a video, and remove a part between two input frames (the start of opening frame, the end of opening frame)... etc, same thing for Ending.

  


  Thanks for the help !

  


• ffmpeg command never work in lambda function using nodejs [closed]

  4 décembre 2022, par Santosh swain

  I am trying to implement FFmpeg video streaming functionality such as Instagram countdown functionality. In this code, first of all, I get records(URLs) from the s3 bucket and then split them according to my need, and then create the command and execute it with exec() belonging to childe_process. in this, I am trying to store the out in some specific folder in lambda function but it was never stored. I thought lambda does allow to write files locally so I am trying to do the direct upload on the s3 bucket by using the stdout parameter of exec()'s callback. guys, please help to do that. I have a question lambda does allow to write content in its local folder ? or if not allow then whats the way to do that thing ? I just share my code please guide me.

  


  
    // dependencies
var AWS = require('aws-sdk');
var s3 = new AWS.S3();
var { exec } = require('child_process');
var path = require('path')
var AWS_ACCESS_KEY = '';
var AWS_SECRET_ACCESS_KEY = '';
var fs = require('fs')

s3 = new AWS.S3({
    accessKeyId: AWS_ACCESS_KEY,
    secretAccessKey: AWS_SECRET_ACCESS_KEY
});

exports.handler = async function (event, context) {

    var bucket_name = "sycu-game";
    var bucketName = "sycu-test";

    //CREATE OVERLAY AND BG_VALUE PATH TO GET VALUE FROM S3
    const bgValue = (event.Records[0].bg_value).split('/');
    const overlayImage = (event.Records[0].overlay_image_url).split('/');


    var s3_bg_value = bgValue[3] + "/" + bgValue[4];
    var s3_overlay_image = overlayImage[4] + "/" + overlayImage[5] + "/" + overlayImage[6];
    const signedUrlExpireSeconds = 60 * 5;


    //RETREIVE BG_VALUE FROM S3 AND CREATE URL FOR FFMPEG INPUT VALUE
    var bg_value_url = s3.getSignedUrl('getObject', {
        Bucket: bucket_name,
        Key: s3_bg_value,
        Expires: signedUrlExpireSeconds
    });
    bg_value_url = bg_value_url.split("?");
    bg_value_url = bg_value_url[0];


    //RETREIVE OVERLAY IMAGE FROM S3 AND CREATE URL FOR FFMPEG INPUT VALUE   
    var overlay_image_url = s3.getSignedUrl('getObject', {
        Bucket: bucket_name,
        Key: s3_overlay_image,
        Expires: signedUrlExpireSeconds
    });
    overlay_image_url = overlay_image_url.split("?");
    overlay_image_url = overlay_image_url[0];


    //MANUAL ASSIGN VARIABLE FOR FFMPEG COMMAND 
    var command,
        ExtraTimerSec = event.Records[0].timer_seconds + 5,
        TimerSec = event.Records[0].timer_seconds + 1,
        BackgroundWidth = 1080,
        BackgroundHeight = 1920,
        videoPath = (__dirname + '/tmp/' + event.Records[0].name);
    console.log("path", videoPath)
    //TEMP DIRECTORY

    var videoPath = '/media/volume-d/generatedCountdownS3/tmp/' + event.Records[0].name
    var tmpFile = fs.createWriteStream(videoPath)
    //FFMPEG COMMAND 
    if (event.Records[0].bg_type == 2) {
        if (event.Records[0].is_rotate) {
            command = ' -stream_loop -1 -t ' + ExtraTimerSec + ' -i ' + bg_value_url + ' -i ' + overlay_image_url + ' -filter_complex "color=color=0x000000@0.0:s= ' + event.Records[0].resized_box_width + 'x' + event.Records[0].resized_box_height + ',drawtext=fontcolor=' + event.Records[0].time_text_color + ':fontsize=' + event.Records[0].time_text_size + ':x=' + event.Records[0].minute_x + ':y=' + event.Records[0].minute_y + ':text=\'%{eif\\:trunc(mod(((' + TimerSec + '-if(between(t, 0, 1),1,if(gte(t,' + TimerSec + '),' + TimerSec + ',t)))/60),60))\\:d\\:2}\',drawtext=fontcolor=' + event.Records[0].time_text_color + ':fontsize=' + event.Records[0].time_text_size + ':x=' + event.Records[0].second_x + ':y=' + event.Records[0].second_y + ':text=\'%{eif\\:trunc(mod(' + TimerSec + '-if(between(t, 0, 1),1,if(gte(t,' + TimerSec + '),' + TimerSec + ',t))\,60))\\:d\\:2}\'[txt]; [txt] rotate=' + event.Records[0].box_angle + '*PI/180:fillcolor=#00000000 [rotated];[0] scale=w=' + BackgroundWidth + ':h=' + BackgroundHeight + '[t];[1] scale=w=' + BackgroundWidth + ':h=' + BackgroundHeight + '[ot];[t][ot] overlay = :x=0 :y=0 [m1];[m1][rotated]overlay = :x=' + event.Records[0].flat_box_coordinate_x + ' :y=' + event.Records[0].flat_box_coordinate_x + ' [m2]" -map "[m2]" -pix_fmt yuv420p -t ' +
                ExtraTimerSec + ' -r 24 -c:a copy ' + videoPath + "";
        }
        else {
            command = ' -stream_loop -1 -t ' + ExtraTimerSec + ' -i ' + bg_value_url + ' -i ' + overlay_image_url + ' -filter_complex "color=color=0x000000@0.0:s= ' + event.Records[0].resized_box_width + 'x' + event.Records[0].resized_box_height + ',drawtext=fontcolor=' + event.Records[0].time_text_color + ':fontsize=' + event.Records[0].time_text_size + ':x=' + event.Records[0].minute_x + ':y=' + event.Records[0].minute_y + ':text=\'%{eif\\:trunc(mod(((' + TimerSec + '-if(between(t, 0, 1),1,if(gte(t,' + TimerSec + '),' + TimerSec + ',t)))/60),60))\\:d\\:2}\',drawtext=fontcolor=' + event.Records[0].time_text_color + ':fontsize=' + event.Records[0].time_text_size + ':x=' + event.Records[0].second_x + ':y=' + event.Records[0].second_y + ':text=\'%{eif\\:trunc(mod(' + TimerSec + '-if(between(t, 0, 1),1,if(gte(t,' + TimerSec + '),' + TimerSec + ',t))\,60))\\:d\\:2}\'[txt]; [txt] rotate=' + event.Records[0].box_angle + '*PI/180:fillcolor=#00000000 [rotated];[0] scale=w=' + BackgroundWidth + ':h=' + BackgroundHeight + '[t];[1] scale=w=' + BackgroundWidth + ':h=' + BackgroundHeight + '[ot];[t][ot] overlay = :x=0 :y=0 [m1];[m1][rotated]overlay = :x=' + event.Records[0].flat_box_coordinate_x + ' :y=' + event.Records[0].flat_box_coordinate_x + ' [m2]" -map "[m2]" -pix_fmt yuv420p -t ' +
                ExtraTimerSec + ' -r 24 -c:a copy ' + videoPath + "";
        }
    }
    var final_command = '/usr/bin/ffmpeg' + command;


    //COMMAND EXECUTE HERE

    await exec(final_command, function (err, stdout, stderr) {
        console.log("data is here")
        console.log('err:', err);
        console.log('stdout:', stdout);
        console.log('stderr:', stderr);
        const params = {
            Bucket: bucketName,
            Key: "countdown/output.mp4",
            Body: stdout,
        }
        s3.upload(params).promise().then(data => {
            console.log("data is here -->", data)
        });
    });
    var tmpFile = fs.createReadStream(videoPath)
    console.log('temp file data:', tmpFile.toString())
};