VIPimp

I am clueless about this stuff... here is what I am trying to do...
I have wmvs/mpgs that I am trying to convert to flash files using ffmpeg, I need to know what is the best recommended settings to set the following to:
-s 480x360 -b 500 -acodec mp3 -ar 22050 -qscale 11
So that the video is good clear quality but the file size is a decent size as well. AND I will be playing them in a flash player with the size of : 600x470

Can someone who has done this before and familiar with it, help me out... I'll owe you a favor, thanks.

VIPimp

hello???

Tempest

Having the video at 480x360 and then having the video player scale it up to 600x470 is going to look like crap at a bit rate of 500.. I'd try 2 things.. I'd try having the video at 600x470 or try 300x235.. scaling by multiples of 2 usually yields better results.. then adjust the bitrate... not sure where you got the 500 from, but when I run ffmpeg it didn't encode at 500kbps as expected... I ended up with 768000 to get 768kbps... You may find that 300x235 1024000 actually has a smaller file size and yet looks better than 600x470 512000...

VIPimp

Thank you for your reply... I will try that out now.

Do you or anyone know if when I have the -qscale, does that overwrite the -b... not sure if both are needed or just one of those.

Thanks again.

VIPimp

Wierd when I try to convert with this size 300x235... I get a error.

fuzebox

For starters I'd drop the qscale argument... Also the -s ###x### should be the size you want the video to be displayed at. Finally, -b requires a value in bps, not kbps, so if you are looking for 500 kbps it should be printed as -b 500000.

VIPimp

For some reason the file size stayed the same when I changed -b 500 to -b 768000... could that be because I had the -qscale in there or is my script screwed up?

And do you know why it wont convert when I have the -s set to 300x235 ? is there a min required size or ?

Thanks you.

VIPimp

Another question to add to the list...

when I convert a file with the ffmpeg crap and I open the flv file in videocharge, it says the bit rate is 0... but when I convert that same original video to flv using other converters and not ffmpeg they all display a bit rate.... any idea why that is?

thanks

Chio

It's likely that ffmpeg is not writing the metadata to the file.

PS Relink's tube script is coming very soon.

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VIPimp

Is that something I should be worried about or is that not important and not affect the quality/play of the video?

Thanks Chio.

Tempest

Forgot to mention that converting to flv requires multiples of 2.. so it won't like 300x235... you'll need to do it as 300x234 or 300x236.. sorry about that.. I ran into the same thing once and I forgot about that.

Once you convert using ffmpeg, you then need to also use a tool like flvtools2 or flvmdi to fix up the flv with metadata and then your problem will go away...

Even when you convert files to flv using videocharge etc., you should still run flvmdi on the files.. On your server you would use flvtools2.. not sure if there are alternatives.

Iron Fist

This thread gives me a headache

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Phoenix

one of the best threads on here in awhile

i am no programmer..but i like ffmpeg..it is inside uugallery which helps me make fesh blog posts

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VIPimp

THANK YOU... just a quick question, if I dont run the flvtools or anything after ffmpeg, is there any downside to that as far as the quality and people being able to view it.

VIPimp

All the different variations of bitrate and size I tried with 1 video, doesnt change it much... its only when I use the -qscale with a value of around 3 is when the video quality is good and somewhere near the original WMV file.

Tempest

Not sure... I had some sync issues, video length reporting etc. in the past that went away once I ran the videos thru flvmdi... yeah it's a bit of a pain getting that stuff all working but if you script the conversions then it can be done all automatically for you.

re: -qscale, truth is I haven't played with all the settings a lot as I just get something decent looking and I'm happy enough since I want the surfers to sign up to a site to get the better quality videos... But after doing some reading I'm going to have to try out -qscale... it appears that if you don't use it, then the video is encoded CBR (constant bit rate) but the quality can vary frame to frame.. but by using -qscale it encodes it VBR (variable bit rate) so the quality stays constant but the bit rate changes.. Could lead to some smaller video size but I suspect you would need to cap the bitrate or set the min max... with -qscale, the values can be 1 to 31 with 1 being the best so with 3 you're almost as good as can be... what are the file sizes like?

I've seen some people post using other paramers like these ones:

-nr 500
-deinterlace
-me_range 25
-i_qfactor 0.71
-g 500

Not sure what -g is used for

someone else on here posted awhile back this stuff

-pass 1 -g 240 -qcomp 0.6 -qmax 15 -qdiff 4 -i_qfactor 0.71428572 -b_qfactor 0.76923078 -maxrate 950 -bufsize 485 -s 512x384 -b 800 -refs 1 -subq 1 -r 25 -acodec mp3 -ab 48 -ar 22050 -ac 1 -y

here's some other parameters I found...

-f flv -deinterlace -nr 500 -s 640x420 -r 30 -b 270k -me_range 25 -i_qfactor 0.9 -qmin 8 -qmax 8 -g 500 out.flv

So many things to play with... Need a degree in video compression to understand it all...

VIPimp

Thanks, a lot of info there... I am not going to even think about all those other parameters lol...

To answer your question... The file I been playing with is a 7mb 1min wmv clip... when I did -qscale 3 it gave me a great video but the size turned out to be around 18mb... -qscale 5 made it around 10mb... without -qscale all the different tests I did, the output file ranged from 4-7mb all of which the quality sucked.

This whole thing is a pain in the ass, so many different options ect.

Thanks again for your help, before reading this I was wondering what CBR and ABR stood for as I came across them now while playing with another software, you answered that for me.

VIPimp

Imagine how I feel.

Tempest

Try dropping the frame rate.... Use -r 15 for a frame rate of 15fps and my tests still look good, not even noticeable... Use to do that in the old days and forgot all about it.

VIPimp

Will try that out...

I am playing with this converter now: Sorenson Squeeze with VP6... my first test with it I got a super quality video with the same file size as what the ffmpeg spit out with its worst quality video. So I'm thinking of just using this to batch convert my wmvs to flv, though it does take longer but seems worth it.

I am just confused again with this on what to put in the fields, maybe you can help me out with that, here is my question from another thread:

Tempest

Don't know about #1 but 2 pass anything should yield better compression than 1 pass..

2. Every 45 frames will be better than every 300.. A key frame is basically an uncompressed frame.. every "frame" after that is compressed as the difference between that keyframe and the current frame. So the more keyframes the better the quality of the video but also the larger the file. I'd assume that 1:1 means that the frame rate of the output is the same as the input file. Again, reducing the frame rate will reduce the file size while still looking good.. Most people can't tell the difference between 30fps and 60fps or even 15fps.

You maintain the aspect ratio...

Yeah, the VP6 compressor is better quality than the older one in ffmpeg... Surfers need to be using a more recent version of Flash in order to watch them though but I'm sure most have upgraded to at least v8.. Not sure if there's licensing issues though with VP6...

Nathan

if you want to still use ffmpeg, here are a few tips:

1) always use the latest SVN version of ffmpeg, do not get a standard release, the app changes 5 times a day.
2) use 2 passes to encode, not just 1
3) never use -qscale, its not going to work right, I tried it for weeks.
4) for high res great quality video, I tend to use these settings:
pass 1: -f flv -vcodec flv -keyint_min 250 -r 25 -ar 44100 -ab 96 -b 3000k -s 1024x820 -g 150 -pass 1 -y
pass 2: -f flv -vcodec flv -mbd 2 -flags +mv0+trell+cbp -keyint_min 250 -r 25 -ar 44100 -ab 96 -b 3000k -s 1024x820 -g 150 -pass 2

The -s of course depends on your original video, thats just a sample size, keep the ratio obviously.

For the player size you suggested, I would use a size of around 540x432 and at that size, these other settings:
-ar 22050 -ab 32 -b 700k

At that quality, stretching the video to the player size you mentioned is going to be totally fine.

keyframes every 250 frames is also completely enough, with -r 25 that means one keyframe every 10 seconds. This is whats going to keep the size of your file down the most. ffmpeg will also lower the bitrate automatically if it achives a qscale of 2.0 with a lower one. Thats what 2 passes is good for.

The keyframe rate does mean of course that framegrabs are only possible every 10 seconds from the flv. So if that is not enough framegrabs for you, build frames for the original wmv instead.

It also means that in a skipable player, they can skip 10 seconds at a time, which usually is fine though in my oppinion.

Your question if running the flv through for example flvtool2 after converting is needed... answer is no, its not NEEDED, but you would be stupid not to. Not using it will ruin the player experience for the user that he got so accustomed to. I at least would never do that.

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ideaworx

any options outside using serverside?... can a guy encode this on win/mac desktop?... i have seen Flix Pro and the Sorenson Squeeze... i have my player ready, and lighttpd installed, but am running into issues on running the scripts w/ my host, thanks

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ideaworx

Edit: Trying Avanti, seems promising, will keep you updated

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VIPimp

Thank you Nathan for all the info.


I think for now I'm going to go with Sorenson's VP6 converter... I'll play with ffmpeg some more later.

Tempest

Nice info there Nathan... Been doing more reading etc. and I saw something that seemed to indicate mencoder will do VP6 but will need to check into that more... Also, it seems like H.264 might be as good or better than VP6, I think it's supported in the latest Flash players and it's open source to some level.. doesn't appear that you can encode with it yet in ffmpeg though.

O MARINA

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Tempest

Check this out.. This guy really knows his encoding... Using H.264 and the new audio compressor AAC, he encoded it at 320x200, the video is ONLY 100Kbit/s and the audio is only 24 Kbit/s..
http://www.flashvideofactory.com/blog.htm#230208

Been trying to use H.264 (you can get the library x264 compiled into ffmpeg) but it's crashing on WinCrap right now...