Why is a video I just recompressed the same file size?

[nomad2224]

I know I'm missing something here, I'm just not sure what it is! I have a FLV video clip that is about 8 minutes long, 18MB in size and I thought I could recompress it using Adobe Media Encoder to a smaller file size. The original file was encoded using the VP6 codec, with a bit rate of 1300 kbps at a resolution of 640 x 480, 30 fps. Audio was MP3 96 kpbs, 22Khz. I thought if I set the encoder to reduce the bitrate to 300 kbps at a resolution of 320 x 480, keeping the same frame rate and audio settings, I would end up with a smaller file size for the video clip. But after the encode was done, I still had a 17MB file....(One MB smaller only!)

What am I missing here...shouldn't I have a smaller file? Doesn't the resolution and bitrate affect the filesize? Or is it because FLV is already so compressed, it really doesn't make difference?
Thanks in advance!

[jagabo]

Yes, file size = bitrate * running time. What did you do with the audio? Is it still compressed?

[nomad2224]

Yes, file size = bitrate * running time. What did you do with the audio? Is it still compressed?

The audio I pretty much left the same...still MP3, 22 Khz, 96 kbps, 2-channel. but I did lower the bit rate considerably from 1300 kbps down to 300 kbps and lowered the resolution to 320 x 240...I can't figure out why the Adobe Media encoder would output a flv file of approximately the same file size?
Can someone explain this to me or am I doing something wrong?

[jagabo]

Is it possible your source has a higher bitrate than you think? Many tools don't indicate bitrate accurately. What did you use?

Sometimes when encoding, if you ask an encoder to compress too much it won't be able to meet your request. But going from 640x480 to 320x200 and asking for ~1/4 the bitrate probably wouldn't give you this problem. At least if you used the same codec and similar settings.

[nomad2224]

I used MediaInfo (on Mac OSX) to view the bitrate and it said it was 1334 kbps, 640x480, at 30fps, VP6. On the newly encoded file, it says, 320 kbps, 320x240, at 30 fps, VP6. The audio I left the same though...would this be why the file is still nearly the same size? I will try to encode with another encoder, perhaps it's the Adobe Media Encoder that is not doing it properly?

[jagabo]

I used MediaInfo (on Mac OSX) to view the bitrate and it said it was 1334 kbps, 640x480, at 30fps, VP6. On the newly encoded file, it says, 320 kbps, 320x240, at 30 fps, VP6.

The video portion of the file should be about 1/4 the size of the original.

The audio I left the same though...would this be why the file is still nearly the same size?

Only if the audio was much bigger than the video. That doesn't seem to be the case here. Did MediaInfo show the same audio bitrate, before and after? Are the running times the same?

[nomad2224]

The audio bitrate was the same and the length is also the same...the only difference is that I am trying to make the FLV small in file size by lowering the resolution to 320x240 and the bitrate to 300 kbps.

[poisondeathray]

Maybe you entered the wrong values?

Or maybe AME screwed up? Try another program e.g. winff, avanti, avidemux