6 Replies Latest reply: Aug 7, 2011 6:05 PM by Colin Brougham RSS

    Target and Maximum Bitrate...

    Dozerbeatz Community Member

      Not finding much info on Target and Maximum bitrate that is under video settings during Export>Media.


      At highest quality, my camcorder is recording at approximately 24mbps.

      I am exporting for Youtube. I know all the settings to use.

      I am just wondering if I should choose the bitrate at which it was recorded, for my target and maximum.

      I am aware that the higher the setting, the larger the file size.


      What are your thoughts?


      On another note. My HD camcorder, JVC GZ-HM300, manual states that any class 4 or higher SDHC card will work.

      I see some of the higher class cards have higher bit rate transfer.

      Do I need to get at least a 24mbps transfer rate SDHC to get full benefit from the 24mbps record bit depth.

      Because I got a standard 16GB class 4 Kodak SDHC for $20 from Meijer, here in Michigan(Meijer is pretty much just like Walmart)


      Description says Class 2, but it has the class 4 symbol, and works with my camcorder.


      What are your thoughts?

        • 1. Re: Target and Maximum Bitrate...
          J. Simon Community Member

          I don't think YouTube will allow a 24 Mbps upload.


          You should not use budget SD media.  All your shots are on that card.  If it fails (and cheap ones do), you're hosed.  Stick with SanDisk Extreme Pro or Panasonic Gold.


          And yes, you'll need at least Class 4 or you won't be able to record on it.

          • 2. Re: Target and Maximum Bitrate...
            Dozerbeatz Community Member

            When I chose a target and maximum bit depth of 24mbps, in the export options for video, it allowed me to upload a test video

            to youtube. And it played. Option for 1080p was there.

            The file was .mp4

            Properties are(on pc when right clicking file and selecting properties>detail tab)





            Noticed on youtube, alot of people choose around 15mbps...to save on filesize.


            The help and manuals for Premiere Pro, do not cover the options in depth.

            Context help when hovering over the option is not the best info either.

            • 3. Re: Target and Maximum Bitrate...
              J. Simon Community Member

              I'm surprised at that.  I thought YT had a maximum limit of 5 Mbps, even for HD.

              • 4. Re: Target and Maximum Bitrate...
                Colin Brougham Community Member

                A larger file or a less-compressed file or a file with a higher bit rate (all of those are functionally equivalent) doesn't necessarily mean a better looking video once uploaded. Practically speaking, a video that has better visual acuity will look better once YouTube runs it through the ringer. My 1080p uploads to YouTube typically hover in the 10-12Mbps range, but they tend to be low motion videos, so they compress well. If you've got a busy video, it may be necessary to crank the bit rate up until you preserve most or at least more of the image fidelity. However, you'll reach a point where you'll just be making a file needlessly large, with no perceptible difference once YouTube does its dance on your video. I would guess that 25Mbps is needlessly high; the recommendation to use 15Mbps or thereabouts is probably sufficient. Testing is the only sure way to know, as there are no hard-and-fast rules when it comes to video encoding--and YouTube takes any of the general accepted practices and dumps them on their head.


                Re: target and maximum bit rate: these come into play when using encoders that employ variable bit rate (VBR) encoding. Target bit rate--like its name suggests--is the bit rate that you want the encoder to shoot for, and use as a relative average. Maximum bit rate--no points for guessing--is the greatest bit rate that you will let the encoder use in segments (typically in divisions called GOPs or groups of pictures) where there is motion or greater visual complexity (highly detailed patterns, or fog, for example). If the encoder was to run full tilt boogie, the maximum bit rate would determine the size of the file; this is roughly equivalent to using CBR or constant bit rate encoding. However, because you've selected a target bit rate (typically, some modicum below the maximum bit rate), the encoder will do its best to maintain that bit rate or lower throughout the video. As an example, my 1080p H.264 encodes for YouTube usually have a maximum bit rate of around 15Mbps, but I set the target at 10Mbps or less. Using 2-pass VBR, and given the nature of the videos I most often encode, my files usually average around 6Mbps. That's what I mean about treating each separate encode as its own entity--you can apply some principles, but in practice, anything goes.


                These Wikipedia articles might offer some interesting insights into the various encoding methods, at least from a bitrate standpoint:


                Variable bitrate


                Constant bitrate


                Average bitrate


                PS: No WAY is Meijer like Walmart The Mitt, reprazent!

                • 5. Re: Target and Maximum Bitrate...
                  Dozerbeatz Community Member

                  Thanks for the great info. I am an audio engineer by trade.

                  Any idea on the transfer rate issue, regarding transfer rate of the card being used in

                  the device. Must the transfer rating of the card be the same or higher as the recording bitrate of the device?

                  I know that isn't a Premiere type question. But Premiere is what Im using..

                  • 6. Re: Target and Maximum Bitrate...
                    Colin Brougham Community Member
                    Must the transfer rating of the card be the same or higher as the recording bitrate of the device?


                    Yes, preferably with a bit of buffer. What actually is this card? Class 2 or Class 4? If it's Class 4, you're probably fine, but it might be worth testing a long recording to be sure. If it's just Class 2, I wouldn't use it.


                    Read up more here: Secure Digital


                    Excerpted from that page:

                    × rating

                    The × rating is equal to 1.2 Mbit/s. It is derived from the standard CD-ROM drive speed of 1.2 Mbit/s (approximately 150 kB/s). Basic cards transfer data up to six times (6×) the data rate of the standard CD-ROM speed (7.2 Mbit/s vs 1.2 Mbit/s). The 2.0 specification defines speeds up to 200×, but unlike the class rating system, does not mandate that ×-ratings measure the card's least sustained write-speed. So, typically, manufacturers provide ×-ratings based on maximum read/write speeds. Furthermore, for most cards, the fastest read speed is typically swifter than its fastest write speed, leading some manufacturers to use read-speed as the ×-rating measurement. Other vendors, such as Transcend and Kingston, use write-speed.[29]

                    This table lists common ratings, the minimum transfer rates, and the corresponding Speed Class.


                    Rating Read Speed
                    Read Speed
                    Write Speed
                    Write Speed
                    7.2 0.9
                    10× 12.0 1.5
                    13× 16.0 2.0 16.0 2.0 2
                    26× 33.0 4.0 32.0 4.0 4
                    32× 38.4 4.8 40.0 5.0
                    40× 48.0 6.0 48.0 6.0 6
                    66× 80.0 10.0 80.0 10.0 10
                    100× 120.0 15.0 120.0 15.0
                    133× 160.0 20.0 160.0 20.0
                    150× 180.0 22.5 180.0 22.5
                    200× 240.0 30.0 240.0 30.0
                    266× 320.0 40.0 320.0 40.0
                    300× 360.0 45.0 360.0 45.0
                    400× 480.0 60.0 480.0 60.0
                    600× 720.0 90.0 720.0 90.0


                    Class 4 write speed is--at maximum--32Mbps, while your footage is +24Mbps. That's pretty close, and remember that write may actually be less because that's maximum burst transfer rate, not sustained rate. Again, the best way is to test.