Reduce Video Stream Resolution

This section provides a tutorial example on how to reduce display resolution of the video stream a SWF file with the '-s nnn:nnn' option on the output file of the 'ffmpeg' command.

Sometimes you want to reduce the video resolution to reduce the SWF file size. This can be done by the "ffmpeg" command as shown below:

   -i input.swf -s nnn:nnn output.swf

"-s nnn:nnn" specifies the new video resolution in pixels for the output file.

Our last sample SWF, Video_and_Audio.swf, has a video stream with a 416x240 resolution. We can reduce it to 208x120:

   -i Video_and_Audio.swf -s 208:120 Resolution_Reduced.swf

Input #0, swf, from 'Video_and_Audio.swf':
 Duration: 00:02:03.96, start: 0.000000, bitrate: 127 kb/s
  Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 128 kb/s
  Stream #0:1: Video: flv1, yuv420p, 416x240, 25 fps, 25 tbr, 25 tbn

Output #0, swf, to 'Resolution_Reduced.swf':
  encoder         : Lavf55.40.100
 Stream #0:0: Video: flv1 (flv), yuv420p, 208x120, q=2-31, 200 kb/s, 
              25 fps, 90k tbn, 25 tbc
   encoder         : Lavc55.63.100 flv
 Stream #0:1: Audio: mp3 (libmp3lame), 44100 Hz, stereo, s16p
   encoder         : Lavc55.63.100 libmp3lame

Stream mapping:
  Stream #0:1 -> #0:0 (flv -> flv)
  Stream #0:0 -> #0:1 (mp3 -> libmp3lame)

Press [q] to stop, [?] for help
frame=321 fps=0.0 q=6.3  size= 641kB time=00:00:12.84 bitrate=408.9
frame=644 fps=643 q=8.9  size=1208kB time=00:00:25.76 bitrate=384.0
frame=960 fps=640 q=5.3  size=1732kB time=00:00:38.40 bitrate=369.6
frame=986 fps=639 q=6.8 Lsize=1775kB time=00:00:39.44 bitrate=368.6

video:1130kB audio:617kB subtitle:0kB other streams:0kB 
   global headers:0kB muxing overhead: 1.578117%

Checking the file size:

C:\herong>dir *.swf
05/27/2014  10:35 PM         1,817,328 Resolution_Reduced.swf
05/27/2014  09:21 PM         1,983,411 Video_and_Audio.swf

Why the SWF file with reduced video resolution is almost the same as the original SWF file? May be the compression on the video data is so good on animation video, I guess.

Now enjoy the video with the reduced resolution:

C:\herong>\local\bin\flashplayer_13_sa Resolution_Reduced.swf

Table of Contents

 About This Book

 Introduction of Adobe Flash

 Adobe Flash Player Plugin for Firefox

 Adobe Flash Player Plugin for Chrome

 Adobe Flash Player Plugin for Safari

 Adobe Flash Player ActiveX for IE

 Using "object" Elements for Flash Files

 Using "embed" Elements for Flash Files

 "mp3player" - MP3 Music Player

 SWFObject - Hidding "object" behind JavaScript

 Flash Player Projector

 SWFTools - SWF File Manipulation Tools

 SWFC Script to Generate Flash SWF Files

 ActionScript Embedded in SWFC Script

 AS3Compile - ActionScript 3 Compiler

 Adobe Flex SDK 4

 SWF File Structure and Tags

 SWF File Processing Rules

SWF Files for Video and Audio Streams

 Video and Audio Stream SWF File Structure

 Installing FFmpeg to Manipulate Video SWF Files

 Playing Movie with FFmpeg "ffplay" Command

 See File Properties with FFmpeg "ffprobe" Command

 Convert File Format with "ffmpeg" Command

 Issue with "ffplay" on SWF Output File

 "ffplay" Interactive Commands

 Break Long Video into Parts with "ffmpeg"

 Concatenate Video Files with "ffmpeg"

 Video/Audio Stream Concatenation Order

 Split Audio Stream Out of SWF File

 Split Video Stream Out of SWF File

 Merge Video and Audio Streams to SWF File

Reduce Video Stream Resolution

 Reduce Video Frame Rate

 Outdated Tutorials


 Full Version in PDF/EPUB