8 Replies Latest reply on Oct 4, 2010 9:08 AM by Jim_Simon

    Selecting "Use Previews" when exporting?

    BarryBrum Level 1

       

      Hello, everyone. Can someone please explain to me the benefit of choosing "Use Previews" when exporting? Does it increase the quality of the final render? If so, what are the comparative values of additional time versus additional quality? Thanks, Brum

        • 1. Re: Selecting "Use Previews" when exporting?
          Colin Brougham Level 6

          Theoretically, it will decrease the quality, as what this command is specifying is that the exporter should use the files you already rendered in Premiere. Depending on the preview codec that is used, you will be recompressing a file that has already been recompressed. The benefit is that the export will be faster, because the video frames don't have to be processed before going to the final compression. Of course, this is sort of a wash, as you have to account for the time that preview rendering ate up.

           

          For quick exports where you might have already rendered a timeline (like for a quick one-off to send to a client), you can tick the Use Previews box, but my feeling is that in real world practice, you typically don't want to use this.

          • 2. Re: Selecting "Use Previews" when exporting?
            Ann Bens Adobe Community Professional & MVP

            If you want good quality don't use the Preview files.

            Make sure Max Render Quality is on for those bits that are not rendered by the GPU.

            • 3. Re: Selecting "Use Previews" when exporting?
              BarryBrum Level 1

               

              Thanks for the quick response, Colin and Ann. I get it, selecting "Use Previews" when rendering saves rendering time but loses some quality. I can see where quick rendering for  a quick view may come in handy, but I lean toward quality even for a personal  preview. Guess I'll not be using the "Use Previews" selection. Thanks again. Brum

              • 4. Re: Selecting "Use Previews" when exporting?
                Jim_Simon Level 8

                As Colin mentioned, whether or not you lose quality will depend on the preview codec used.  I personally use Uncompressed specifically so there will be no quality lost.  Using Preview files for me will give me the best possible quality and speed up exports.

                • 5. Re: Selecting "Use Previews" when exporting?
                  SteveHoeg Adobe Employee

                  That is not nescessarily true in all cases for uncompressed. If your preview format doesn't match the frame size or bit depth of your output format you can loose quality, even if the preview format is uncompressed.

                  • 6. Re: Selecting "Use Previews" when exporting?
                    Jim_Simon Level 8

                    Is it even possible for those specific settings NOT to match your sequence?  In CS4 I don't think it is.

                    • 7. Re: Selecting "Use Previews" when exporting?
                      SteveHoeg Adobe Employee

                      Starting in CS5  it is possible to have preview size not match sequence size. You can  have HD sized preview files for a 4k R3D sequence. Even if your preview size does match your sequence size perfectly, if you are outputting to a resolution not matching your preview size (eg HD->SD, 1080p->720p, SD->square pixel for web, etc) then there can be a loss of quality using uncompressed preview files. When in doubt play it safe and don't use preview files if you care about quality.

                      • 8. Re: Selecting "Use Previews" when exporting?
                        Jim_Simon Level 8

                        if you are outputting to a resolution not matching your preview size (eg HD->SD, 1080p->720p, SD->square pixel for web, etc) then there can be a loss of quality using uncompressed preview files

                         

                        But in that case, would you not suffer the same hit even without using previews?  If the preview matches the quality of the original, how would using one over the other make any difference in the final export quality?