4 Replies Latest reply on Aug 3, 2012 7:20 PM by owiseone61755

    1080i 60i source footage loss of quality encoding

    owiseone61755 Level 1

      I shot footage using my canon vixia hf m31 on the 60i setting and when i watch the raw .mts files the resolution and sharpness are excellent.


      However when I try to edit some footage together in premiere pro CS 6 and encode it i lose the some of the quality.  whether i export as 1080i 30i mp4 or 1080p 30p mp4 that sharpness gets a little dull.


      Is it possible to retain the quality of the original source file??


      Also is "deinterlacing" the process of converting my 60i to 30p like for example the purposes of youtube uploads?  Does that cause a loss of quality?  Should I have just shot the original footage in 30p for future reference if my final product is intended for web uploads and isnt fast moving "sports" action?

        • 1. Re: 1080i 60i source footage loss of quality encoding
          josephs51576386 Level 3

          H.264 (.mp4 container) is a lossy format. When you export using it you are bound to lose some quality. What bitrate settings are you using? Also what are your sequence settings? Also are you using the modify>interpet footage option to make it progressive rather than just selecting progressive in the export option?


          The only way you can avoid losing quality is to encode it to a lossless format like Lagarith or UT. You can also use a visually lossless option such as DNxHD or Cineform, or ProRes. However as far as I know youtube doesn't work when you upload in lossless formats unless something has changed because around a year ago I tried uploading some lossless content and youtube said it wasn't supported. So what I do now is just turn the bitrate up fairly high and accept the fact that it will take longer to upload to youtube but at least my footage will look better.


          Also to answer your question about deinterlacing the answer is yes basically if you make something that is interlaced into progressive  than that would be considered deinterlacing. While it doesn't really cause a notable loss in quality it's not something you want to do unless you need to. However in my experince youtube generally doesn't play nicely with interlaced content if you have something with a lot of lower thirds in it. It usually ends up making your graphics look blurry/jagged at the same time.


          Honestly in the future I would recommend you shoot everything in Progressive to begin with if that's what you're end game goal is going to be. Because it is just easier to do things that way.  In my experince for uploading things to youtube I generally prefer uploading my content as progressive because otherwise you'll find when you-tube encodes your footage after you upload it to them that your graphics and sometimes footage will end up looking screwed up.

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          • 2. Re: 1080i 60i source footage loss of quality encoding
            owiseone61755 Level 1

            First off, thanks for the help!  I especially appreciate you speaking in terms a novice can understand. 


            To answer your questions, I had no idea about modify>interpret footage so just now I went into my project and modified all the clips that were used in my sequence.  Will this edit apply to all the edited clips that are already on my timeline?  Or do I have to drag them back over to the time line and re edit now that the original clips say "conform to: progressive scan(no fields)" or will that edit be applied automatically on export?  I'd hate to have to set up all my clip edits again.  There are many.


            This was my first ever project so when I started it I had no idea 60i meant 30i so my project settings we're 1920x1080 progressive 60fps.  Does this matter or should I copy and paste my timeline into a new sequence with 1080i 30i as the original source before I convert to progressive and export?


            The bit rate I've used is the youtube default which is 8mbps.  Can you explain a little about bit rate?  I've noticed if I turn the bit rate up, the file size gets large.  How much of a quality difference can this make?  Like going from 8 to 24 for example?  The video was shot in 24 mbps according to the camcorder settings.  Also, bit rate and vbr 1 or 2 pass.  What does this do and how does it play a factor?


            Lastly, I just noticed when I right click on a clip in my timeline theres something called "field options" and an option that says "always deinterlace".  Would this have the same effect as modify>interpret??


            Ok and one more question!  Do I have to encode the file that goes into the encoder from the "export settings" in order for the modify>interpret footage to take effect?  Or once its in the encoder can I select other presets(like youtube) and it will still interpret the footage?  I notice in the export settings the only mpeg4 option is "3gpp 352x288" what is that?  why is there no 1920x1080 mpeg4 option till I get to the presets??


            Thanks again!

            • 3. Re: 1080i 60i source footage loss of quality encoding
              josephs51576386 Level 3

              It will effect all clips that are already in the timeline. So for example if you click on "sourceclip1" in the bin and modify it to progressive then all instances of "sourceclip1" will automatically be updated in the timeline.


              To answer your second question yes you should copy and paste your timeline into a timeline with the correct frame rate. Just create a new sequence that is 1920x1080 that is the correct frame rate. Since you want it to be progressive and since at this point you have conformed your footage to progressive I'd recommend using a progressive seqeunce, then also exporting your final product as progressive since your final destination is for web viewing.


              To answer your third question about bit-rate basically bitrate will amost always directly effect the picture quality although there is also a point of "deminishing returns".  A higher bitrate = higher quality however you still always want to avoid encoding something over and over again unless dealing with a lossless format. Generally speaking the lower the bitrate the lower your quality will be.


              VBR 1 pass simply goes threw your video 1 time and because of that it isn't as efficent as a VBR 2 pass is. When you use a 2 pass it uses one pass to evaluate where your video needs the extra bitrate at and then during the second pass it actually applys the information that it gained on the first pass in regards to what section of video needs more  headroom in  the bitrate area.  For web video I always recommend using a 2-pass. You'll end up with better looking video at around the same size. 


              In my experince I don't like using the option always deinterlace in the timeline mainly because then you have to remember to click each individual instance of that clip inside your timeline verses just using the option that is from your bin. The bin option of using the modify actually changes every instance so as far as I know that is the only difference between the two options. I always use the modify option though in most cases since it will affect every instance of the clip.


              The mpeg-4 format option in premiere uses h.263 which isn't near as efficent as h.264. So I'd recommend you just stick with selecting h.264 format option and using their 1080p you-tube preset, however I'd recommend setting the max bit-rate at like 14 and turning the target up to 11 just to give yourself a little quality bump.  Also always stick with 2-pass. To answer your last question what you need to do is after you have modified all your footage I always just scrub threw my timeline really quick then go to file-export-media and send it to Adobe Media Encoder, then you know you just sent your up to date copy to AME. Then you'll be good to go.

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              • 4. Re: 1080i 60i source footage loss of quality encoding
                owiseone61755 Level 1

                Hey thanks for all the info man, really appreciate it!