9 Replies Latest reply on Aug 14, 2009 7:30 PM by Jim_Simon

    Media Encoder (AMC) F4V - none of the video setting effect file size????

    jjx Level 1

      When I used to use sorenson squeeze, mov  i could get a web flick down to 15 MB by reducing frame rate or size.

       

       

       

      when using AMC - F4V - no matter what size or settings the same movie satays at about 34MB (with olny slight varistions if i tweek audio)

       

      How do i get the file size smaller if none of the video setting effect file size????

        • 1. Re: Media Encoder (AMC) F4V - none of the video setting effect file size????
          Jim_Simon Level 8

          The only significant change in final file size will come from lowering the video bitrate.

          1 person found this helpful
          • 2. Re: Media Encoder (AMC) F4V - none of the video setting effect file size????
            jjx Level 1

            got it, thanks

             

             

            do you happen to know if CBR VS 1 VS 2 pass make any real difference using this format?

            • 3. Re: Media Encoder (AMC) F4V - none of the video setting effect file size????
              Harm Millaard Level 7

              Not in size, but depending on your footage maybe in quality, with 2 pass VBR have the advantage in quality and CBR having the advantage in speed.

              • 5. Re: Media Encoder (AMC) F4V - none of the video setting effect file size????
                Harm Millaard Level 7

                Yes, 2-pass takes around twice as long as single pass.

                1 person found this helpful
                • 6. Re: Media Encoder (AMC) F4V - none of the video setting effect file size????
                  Curt Wrigley Level 4

                  JSS1138 wrote:

                  The only significant change in final file size will come from lowering the video bitrate.

                  But reducing frame size and frame rate will have a significant impact on file size because they allow you to lower the bit rate and still have good quaility.

                  • 7. Re: Media Encoder (AMC) F4V - none of the video setting effect file size????
                    Colin Brougham Level 6

                    In the limited amount of comparison testing I've done, I've found that 2-pass VBR files are consistently smaller than CBR files, all other things being equal. They're not always a great deal smaller, but they've never exceeded the size of the CBR files, and this goes for any type of encoding I've done, whether it's MPEG-2 for a DVD, or a web format like WMV, FLV (VP6), or H.264. This seems to be true even when the target and the maximum bitrate for the 2-pass VBR files match the bitrate "quantity" of the target bitrate of the 1-pass CBR files, and I've noticed this in any encoding application I use, whether it's AME, Sorenson Squeeze, or TMPGEnc Xpress. When analyzing my VBR-encoded files using an application such as MediaInfo, the average bitrate that is reported is never even close to my max bitrate, and is usually well under my target bitrate.

                     

                    I see two reasons for this:

                     

                    1. If you're encoding with CBR and set your bitrate at 1000kbps, for instance, the encoder will simply allocate 1000kbps of bandwidth (divided by the frame rate) to each and every frame of video, regardless of how complex or simple each frame is. Each frame will be compressed to as near 1000kbps (divided by the framerate) as possible. Using CBR, you can more or less estimate the end file size by multiplying the bitrate by the duration in seconds. Think of it as filling a series of water glasses: with CBR, you fill each glass full, regardless of how much each individual actually wants to drink.

                    2. If you're encoding with 2-pass VBR and set your maximum bitrate to 1000kbps and (for argument's sake) your target bitrate to 1000kbps as well, the encoder will use the first pass to figure out how much available bandwidth is needed at each individual point of time, and that writes that to a log file that the second pass of the encoder then uses to properly allocate those available bits to the frames that need them the most. If a particular passage of the video can be encoded at a lower bitrate, and still maintain a prescribed level of visual quality, the encoder will simply put the squeeze on a little more. Back to our water glass analogy from above, this is the equivalent of filling each water glass with only as much water as each individual wants.

                      For example, using the max/target bitrate set above, a low-motion/low-complexity passage of video may be able to be encoded at only 500kbps and yet maintain the visual quality of 1000kbps. This results in a fewer bytes needed to encode that particular duration of the video, and usually there are multiple sections in a video that can be treated as such. This has a cumulative effect and subsequently results in a final encoded video that has a smaller file size than it would had it be encoded at the same bitrate, but with CBR encoding.

                     

                    I'm not a software engineer or mathemagician, so I can't back all this up with empirical evidence, but in real-world practice, these have been my observations. Long story short: I always use 2-pass VBR for web-distributed encodes, and enjoy both smaller and better-looking files, at the expense of a coffee break.

                    • 8. Re: Media Encoder (AMC) F4V - none of the video setting effect file size????
                      Colin Brougham Level 6

                      But reducing frame size and frame rate will have a significant impact on file size because they allow you to lower the bit rate and still have good quaility.

                      Curt,

                       

                      This is a very good point, about being able to lower the bit rate when you lower the frame rate. I think this is an oft-overlooked element in video encoding: that cutting your frame rate in half (for example from 30fps to 15fps) doesn't automatically mean a file that is half the size. Since bitrate is a "constant", if you keep it the same even though your halving your frame rate, you're simply allowing those remaining frames to have a bigger slice of the bitrate pie. Each frame will look better, relatively speaking, but each frame will also contribute more to the file "weight". The result, obviously, is a video encode that looks great (or better, anyway), is stuttery, and is no smaller than it was before.

                       

                      I remember this was a head-scratcher for me for awhile when I started authoring 24p DVDs. I couldn't for the life of me figure out why my 24p MPEG-2 files were the same size as my 60i MPEG-2 files, from the same source. C'mon--there are fewer frames here! You should be smaller! Of course, those initial encodes looking beautiful, even if they didn't fit on the DVD...

                       

                      Anyway, thanks for making this point... sorry I had to go around the block to say that

                      • 9. Re: Media Encoder (AMC) F4V - none of the video setting effect file size????
                        Jim_Simon Level 8

                        But reducing frame size and frame rate will have a significant impact on file size because they allow you to lower the bit rate and still have good quaility.

                         

                        That is true, but only if one actually does lower the bitrate.  The OP seemed to have left that step out.