Archive for the ‘YouTube’ Category

YouTube Upload Formats: “That Old Chestnut”

Friday, September 6th, 2013


When uploading to  YouTube (or Vimeo or indeed most online video services), the uploaded video need not be in the format that will ultimately be served to the audience. Instead, it is essentially in an an archive role, and based on this archive, the services will (now and/or in the future) encode their own copies at various resolutions.   The uploaded “archive” should therefore be of the best quality, and is not constrained to be in a format that plays well on most target devices.

YouTube defines two upload-formats: Standard (for typical enthusiast videos) and Enterprise (for serious matter such as movies or corporate productions).  A 5-minute video in Standard format may be about 350 MB while in Enterprise format it may be around 2GB.  So for practical purposes, Enterprise format requires an Enterprise internet-connection.

  • Standard-Level Encoding:
    • YouTube gave good results when the video was uploaded in H264 at 8 mean 16 max Mbps.
      • I (currently) believe this is a good practical upload-format to use in most cases.
        • It has given good results for general scenes (in the experience of others as well as myself).
      • My maximum bitrate (16Mbps) exceeds Adobe’s YouTube 1080 preset, which defines 8Mbps mean=max.
      • However it is way below YouTube’s official (and YouTube-expert-confirmed) advice of 50Mbps (mean=max) for Enterprise-class (productions and internet connections).
        • I wonder whether such high bandwidth is only really of advantage to fast-changing scenes e.g. foamy sea-spray or to future derivation of 4K from it etc.
        • It could presumably be regarded as a useful format for archiving in general, at least where no subsequent significant levels/color manipulation was intended.
    • Poor results were obtained when uploaded (mistakenly) at 720p25 at 5 Mbps (mean=max), especially when played (from YouTube) at lower resolutions, when blocking was apparent.
    • I am not too sure about Adobe Media Encoder’s YouTube 1080 preset, maybe it is slightly under-specified, the audio bitrate as well as the video bitrate.
  • Enterprise-Level Encoding via custom settings in Adobe Media Encoder (version CC of August 2013)
    • These are essentially “BluRay-like” / “Gold Standard” formats, from which YouTube’s servers can derive multiple present-day play-formats.  Their use should also result in good-quality archive material from which, in future, to derive further (as yet uninvented or not-yet-popular) formats.  To “stand the test of time”…
    • Audio 320Kbps
    • Video:
      • Bitrate:
        • 50 Mbps for 1080p (25 fps)
        • 30 Mbps for 720p (25 and 50 fps?)
      • Level:
        • 4.2
          • General H264 advice is use lowest Level that permits (includes as an option) your required bitrate.
          • Level 4.2 additionally has a reasonable number (hence density) of macro-blocks.
      • Mode
        • Mode should be [High] (as opposed to [Baseline] or [Main] ).
          • [High] implies CABAC encoding (which is computationally-intensive but gives superior-quality results) and two B-frames.
            • These are both requirements for Enterprise-class YouTube uploads.
        • We are essentially uploading an archive format as opposed to playable, so we don’t care how computationally intensive it is.
  • Key Frames Distance
    • Same thing as GOP size or length (I assume).
    • YouTube’s official spec says it should be half the frame-rate…
      • e.g. 12 in the case of 25 fps ?
      • As opposed to a general rule of thumb (elsewhere) of three times the fps.
        • e.g. 75 frames in the case of 25 fps or 150 frames for 50 fps.
          • Scary numbers…
          • Various people report less smooth motion when shorter keyframe distances are used.  But maybe that only applies to lower bitrates?
  • B-Frames:
    • This is the number of bi-directional (B) frames between I and P frames, e.g. a value of 3 would give: [IBBBPBBBPBBBPBBBP]
    • The recommended number is 2 for YouTube-Enterprise context (as opposed to 3 in some other contexts).


I had shot two videos on my trusty Sony EX3 camera, one at 1080p25 the other at 720p50.

Reason?  The first one was a standard live entertainment event, demanding some run&gun, hence I shot it at highest definition.  However the other event was a sporting one, and 50 fps provides more potential for handling fast action in various ways (smoother action or slow motion).  On this camera, 50fps was only possible in 720p, not 1080p (the camera can also record 1080i50 (fields/second), from which one can generate motion-estimated full-frame 1080p50, but that is extra work, not conducive to productivity, hence best avoided).

On my Adobe CC editing system, I completed the 720p50 video first, then encoded that to 720p25 (Adobe Premiere CC’s YouTube preset, of 5Mbps, mean=max) for checking and eventual upload to YouTube.  A day or two later I completed the (longer) 1080p50 video, then similarly encoded that to 720p25 for smaller file and faster upload for the draft/check process.

Then came time to upload the 1080p25 video to YouTube, initially with distribution set to Private.  It was late and I forgot to change the encoder setting to 1080.   Mistakes can happen, that’s why it was initially made Private and why a test-play or two at various resolutions was in order.   When played (from YouTube), not only did this reveal the reduced resolution, unexpectedly there was also some very obvious blocking on fast action, especially when the YouTube video was played at lower resolutions.

…Which of course illustrates the exact purpose of Quality-Checking is for, in the workflow…

Naturally the first thing to so was re-encode at 1080 (duh!).  Adobe’s YouTube-preset for this used a VBR bitrate 8 Mbps (mean=max).    Then also I also increased the maximum bitrate to 16.  I hadn’t time for experimenting, so I just made a best-guess.  Result: Success!  Following upload of the result to YouTube, test-plays of this looked far better in all respects at the various play-resolutions.

So I did some further web-research … which led me down a (finite) “rabbit-hole” wherein I discovered the existence of two kinds of upload-format standards: Standard (a few Mbps) and Enterprise (BluRay-ish, tens of Mbps).  Aghast at the latter, I did further web-searching, which confirmed it.


YouTube Slide-Show Creation

Monday, August 12th, 2013

Lessons from creating a YouTube slide-show – which I did for the first time just now:
(Can’t recall exactly what I did, but it was approximately as follows)

To create a video from your own images via YouTube’s on-line timeline editor:

  • Ensure you are logged-on to YouTube under intended account
  • Upload (not dropdown) > Photo slideshow (Create)
  • -> Select the photos for your slideshow: Upload photos
  • Use [Advanced editor]
    • (Now you should see a video editing timeline)
    • Alter the image order, transitions, durations to suit
    • For a background-free lower-third text overlay:
      • Banner, set [Position]=[Bottom], [Text size]=[Small], [Opacity]=[0].
  • Select the Thumbnail.
  • Add text intro/comment.
  • etc.
  • SAVE

To specify the video as a response to one or more other videos:

  • Ensure you are logged-on to YouTube under intended account
  • Go to the target-video
  • Post (initially as if you were making a text comment)
  • Specify it as being a video-response
  • Select which of your videos you want to be the response.
  • SAVE

Nokia N95 Variable Frame-Rate

Thursday, January 19th, 2012

I came across some old videos I shot on a Nokia N95 and pulled these into Adobe Premiere.  However the individual video clips were each listed with a different framerate, hovering vaguely around 29 fps (27.08 up to 29.45).   Questions:

  • What does that even mean?
    • From web-search, it sounds like it’s an average, and N95 framerates within a given recording can vary wildly
      • e.g. between 6 and 38 fps.
  • How do various apps etc. handle such material?
    • YouTube:
      • In 2009 at least, it sounds like YouTube went for the minimum fps in any such clip.
    • Adobe Premiere
      • Seems to go for the average
        • I dragged a N95 clip on the “New Sequence” button and the resulting sequence had the clip’s average framerate.
      • Presumably just duplicates/drops frames as required to maintain the Sequence’s framerate.
    • GSpot (video analyzer):
      • For a clip reported by Adobe Premiere to be 28.81 fps, GSpot reported it to be 29.412 fps.
        • Misleading info from one or other or both…


Vimeo Upload Formats

Monday, May 2nd, 2011
  • H264 Encoder Tips:
    • Some recommend the use of Handbrake (free encoder) over that in Sony Vegas 9 and earlier.
    • Sony Vegas 10 uses an updated version of the MainConcept encoder (for H264 etc.) than Vegas 9 etc.
      • I don’t know how this compares to Handbrake.
  • Levels: Studio/Broadcast, 0-235.
    • Any levels outside this range will be preserved by the encode/decode but will get clipped at 16=black and 235=white.
    • Levels within the range will play back in Vimeo at 0-255 RGB on computer display.
  • But what of gamma/colorspace?  601 or 709 or what?
  • Framerate:
    • 30fps (as in USA) or 25fps (as in Europe etc.).
      • For nicer motion, might be worth mo-comp retiming 25 fps to 30 fps?
  • Resolution:
    • 640×480 for standard definition
    • 4:3 video, 853×480 for widescreen DV
    • 1280×720 or 1920×1080 for high definition.
  • Pixel Aspect:
    • Square, i.e. 1:1″ or “1.00”
  • Interlacing:
    • None (Progressive)
  • Encoding
    • MP4-(H264+AAC).  Other formats also possible but this one is probably the most popular.
      • H264:
        • Use 2000 kbits/sec for standard definition 4:3 video, 3000 kbits/sec for widescreen DV, or 5000 kbits/sec for high definition footage.
        • Profile = Main ?
        • Reference frames = 2 (default)
          • Each macroblock (or part of it?) can be predicted from a different reference frame.  Result can be higher quality but increased encoding time – since each Ref. Frame implies its own motion estimation.  A default of 2 or 3 is about right.  Higher values tend only to be helpful for animations.  Values above 5 rarely help.
        • Deblocking filter = Yes ?
      • AAC: 320 kbps / 44.1 kHz
      •  If you give them non-streaming source, the upload servers must do an extra preliminary pass to find the metadata, taking up more time and resources than is necessary. This has a cumulative effect on overall server response.


Sony Vegas & High-Definition (HD) for YouTube

Friday, June 25th, 2010

Using Sony Vegas to produce High-Definition (HD) material for YouTube, from HD sources: