How to use ffmpeg converting video without decreasing of quality

[hno]

HI every one .

This is how I convert videoes to flv but the quality is decreasing very much .

passthru("$ffmpegpath -i uploads/$video_name -ar 22050 -ab 32k -f flv -s 480x800 uploads/vid.flv");

 

How can I convert videos without any decrease of quality ?

 

Thanks

[QuickOldCar]

Don't you set what encoder to use?

 

You can try setting the bitrate to somewhere around -b 400k , and see how it does.

 

If neither -b:v nor -crf are set, the encoder will use a low default bitrate and your result will probably be poor. Always supply one of these options—ideally both.

 

If this helps you at all, I created a casting script in linux that returns extremely nice quality.

Granted I capture my screen and send this to a host, but you can modify it and also save as file.

 

I guess one reason am showing you this is to show that default is not always best, should have more parameters and tell it exactly what you want as a result.

#!bin/bash
#settings can adjust
#list of stream hosts
SecureSaw="rtmp://flash.sawlive.tv:2139/flash/stream_key";
Saw="rtmp://publish.sawlive.tv/flash/stream_key";
JTV="rtmp://live.justin.tv/app/stream_key";
Ucaster="rtmp://ucaster.eu/live/username?key=stream_key";
Mips="rtmp://mips.tv/live/username?key=stream_key&id=id";
Ustream="rtmp://1.16711620.fme.ustream.tv/ustreamVideo/stream_key";
Zecast="rtmp://live.zecast.tv/zecast/username";#http://zecast.tv/channel.php?id=username
Veemi="rtmp://live.veemi.com/live?u=username&p=stream_key/username";#http://www.veemi.com/watch?v=username
Cast7="rtmp://xxx.cast7.eu/onlive?key=stream_key/username";#http://cast7.eu/index/stream/name/username&sid=id
#select which stream host to use
StreamHost="$SecureSaw";
#video capture in and out
#keep in 8px increments or makes encoder do lots of extra work
VideoInWidth="1024"
VideoInHeight="768"
VideoOutWidth="1024"
VideoOutHeight="768"
WidthOffset="0"
HeightOffset="0"
#video cropping
CropTotalWidth="1024"
CropTotalHeight="576"
WidthCrop="0"
HeightCrop="104"

VideoFramesPerSecond="30" #suggest 24-30
VideoQuality="10" # suggest 10-30 , range is 0-68 , lower number is better quality
KeyFrames="2" #suggest 1-2
NumberAudioChannels="2" #suggest 2 stereo , 1 mono
NumberCPUcores="4" #count your logical cores
VideoBitrate="450k" #try 500k ,varies your upload speed and quality of video/audio sending
AudioBitrate="96k" #suggest 64,96,128
 
#STOP RIGHT THERE!!!
#you should not change anything below unless know what they all do
VideoInResolution="$VideoInWidth"x"$VideoInHeight"
VideoOutResolution="$VideoOutWidth"x"$VideoOutHeight"
avconv \
-f x11grab -y -s "$VideoInResolution" -g "$KeyFrames" -r:v "$VideoFramesPerSecond" -i :"$WidthOffset"."$HeightOffset" \
-f alsa -ac "$NumberAudioChannels" -i pulse -vol 1024 \
-c:a libmp3lame -ar 44100 -threads "$NumberCPUcores" \
-b:a "$AudioBitrate" \
-c:v libx264 -pix_fmt yuv420p -vsync 1 -crf "$VideoQuality" -s "$VideoOutResolution" \
-vf crop="$CropTotalWidth":"$CropTotalHeight":"$WidthCrop":"$HeightCrop" \
-b:v "$VideoBitrate" -minrate "$VideoBitrate" -maxrate "$VideoBitrate" -bufsize "$VideoBitrate" \
-y -f flv "$StreamHost" \

Edited April 12, 2014 by QuickOldCar

[hno]

Thanks for the reply

Could someone please give me a code for converting videos to x264 ?

I've tested several codes but non of the worked .

 

Thanks

[QuickOldCar]

Take a look here, explains and shows example codes, it really depends what the purpose is.

https://trac.ffmpeg.org/wiki/x264EncodingGuidehttps://trac.ffmpeg.org/wiki/x264EncodingGuide

 

Is a lot of older ffmpeg codes out there, they were changed a few years ago.

 

 

ffmpeg -i input -vcodec libx264 -preset fast -tune film -profile main -crf 22 -threads 0 output