just a follow up question in relation to SMPTE / frame accurate playback: As
far as I can tell there is nothing specified in the HTML5 specs that will
allow us to determine the actual frame rate (FPS) of a movie? In order to do
proper time-code calculations it's essential to know both the
On Jan 11, 2011, at 9:54 AM, Rob Coenen wrote:
just a follow up question in relation to SMPTE / frame accurate playback: As
far as I can tell there is nothing specified in the HTML5 specs that will
allow us to determine the actual frame rate (FPS) of a movie? In order to do
proper time-code
Eric, not sure if I understand what you mean. Are you referring to digitally
encoded files where frame #1 has a different duration than frame #2?
On Tue, Jan 11, 2011 at 6:10 PM, Eric Carlson eric.carl...@apple.comwrote:
On Jan 11, 2011, at 9:54 AM, Rob Coenen wrote:
just a follow up
On Jan 11, 2011, at 12:54 PM, Rob Coenen wrote:
Eric, not sure if I understand what you mean. Are you referring to digitally
encoded files where frame #1 has a different duration than frame #2?
Exactly, every frame can have an arbitrary duration so frame rate may have
no meaning. Even in
Intresting- I didn't know that variable frame-rate videos were actually
being used for HTML5 video.
But still- the vast majority of all video uses a fixed frame rate- ever
since Eadweard Muybridge invented 'motion picture' back in 1878.
For example, most hardware these days record in SMPTE
On 12/01/2011 10:58 a.m., Rob Coenen wrote:
Intresting- I didn't know that variable frame-rate videos were actually
being used for HTML5 video.
WebM videos have no fixed frame rate. This format is supported in
Firefox 4, Chrome, and Opera.
Chris P.
Chris, maybe I'm wording it incorrect, but when I run the mediainfo utility
on my test file it reports frame rate: 25.000 fps
(test for yourself with my test file:
http://www.massive-interactive.nl/html5_video/video/timecoded.webm)
I can imagine there are 'virtual' frames, where say frame 1 to 10
why does the frame rate make any difference on the accuracy of seeking to a
time? Imagine a video that runs at 1 frame every 10 seconds, and I seek to 25
seconds. I would expect to see 5 seconds of the third frame, 10 seconds of the
4th, and so on.
On Jan 11, 2011, at 18:54 , Rob Coenen
Hi David- that is b/c in an ideal world I'd want to seek to a time expressed
as a SMPTE timecode (think web apps that let users step x frames back, seek
y frames forward etc.). In order to convert SMPTE to the floating point
value for video.seekTime I need to know the frame rate.
-Rob
On Tue,
OK, but it does seem kinda a tautology if you say I want to use a
time-expression that represents fractions of seconds as frame numbers, and it's
not very accurate if there aren't very many frames/second... !
On Jan 11, 2011, at 23:40 , Rob Coenen wrote:
Hi David- that is b/c in an ideal
On 12/01/2011 11:20 a.m., Rob Coenen wrote:
I can imagine there are 'virtual' frames, where say frame 1 to 10 is
actually the same frame and internally encoded as frame 1 with a duration of
10 frames?
Yes, as I understand it, this is a legal encoding.
Even then I'd like the 'virtual' FPS of
David I agree- however that's common practice in any video editing tool, in
any digital video camera, etc. It's the defacto industry standard for anyone
working with digital video.
I'm just trying to make readers of this list aware of the fact that HTML5
does a great job in video-play back, but
These goals are orthogonal though - stepping between frames is valuable
whether they are regularly spaced or not.
Timecode is a representation that comes from the legacy video world that
does assume a uniform frame rate
On Tue, Jan 11, 2011 at 2:40 PM, Rob Coenen coenen@gmail.com wrote:
Hi
On Tue, Jan 11, 2011 at 5:40 PM, Rob Coenen coenen@gmail.com wrote:
Hi David- that is b/c in an ideal world I'd want to seek to a time expressed
as a SMPTE timecode (think web apps that let users step x frames back, seek
y frames forward etc.). In order to convert SMPTE to the floating
On 11 Jan 2011, at 18:10, Eric Carlson wrote:
On Jan 11, 2011, at 9:54 AM, Rob Coenen wrote:
just a follow up question in relation to SMPTE / frame accurate playback: As
far as I can tell there is nothing specified in the HTML5 specs that will
allow us to determine the actual frame rate
Right - but that foregoes a bit how subtle the SMPTE timecode definition is
(http://en.wikipedia.org/wiki/SMPTE_time_code is a good start) - and this is
exactly why it is defined in such odd a manner (as you do have exactly this
tautology problem between, say, NTSC and PAL).
So yes - you want
I guess that I'm looking at HTML5 from the POV as a video-producer rather
than a video-consumer.
As a producer I'm much more intrested in the legacy video formats. The way
video is being produced is simply on a frame-by-frame basis. I cannot think
of any 3D animation tool video sequencer, video
On 11 Jan 2011, at 23:00, Chris Pearce wrote:
On 12/01/2011 11:20 a.m., Rob Coenen wrote:
I can imagine there are 'virtual' frames, where say frame 1 to 10 is
actually the same frame and internally encoded as frame 1 with a duration of
10 frames?
Yes, as I understand it, this is a legal
On 11 Jan 2011, at 23:46, Kevin Marks wrote:
These goals are orthogonal though - stepping between frames is valuable
whether they are regularly spaced or not.
Timecode is a representation that comes from the legacy video world that
does assume a uniform frame rate
Not sure if they are
On 11 Jan 2011, at 23:57, Glenn Maynard wrote:
On Tue, Jan 11, 2011 at 5:40 PM, Rob Coenen coenen@gmail.com wrote:
Hi David- that is b/c in an ideal world I'd want to seek to a time expressed
as a SMPTE timecode (think web apps that let users step x frames back, seek
y frames forward
On 12 Jan 2011, at 00:48, Dirk-Willem van Gulik wrote:
the clock relative to shutter/gating to the end user - as this is what you
need to avoid flicker, interlace issues, half the frame showing the next
scene, etc.
Apologies - got some private mail asking for examples. So the simplest
On 12/01/2011 1:37 p.m., Dirk-Willem van Gulik wrote:
On 11 Jan 2011, at 23:00, Chris Pearce wrote:
Even then I'd like the 'virtual' FPS of the WebM file exposed to the
webbrowser- similar to how my other utilities report a FPS.
If the 'virtual' FPS value isn't provided by the container, and
On 12 Jan 2011, at 01:17, Chris Pearce wrote:
On 12/01/2011 1:37 p.m., Dirk-Willem van Gulik wrote:
On 11 Jan 2011, at 23:00, Chris Pearce wrote:
Even then I'd like the 'virtual' FPS of the WebM file exposed to the
webbrowser- similar to how my other utilities report a FPS.
If the
On 12/01/2011 2:22 p.m., Dirk-Willem van Gulik wrote:
On 12 Jan 2011, at 01:17, Chris Pearce wrote:
I cannot think of a format where this would in fact be the case - but for a few
arcane ones like an animated push gif without a loop.
WebM can be variable frame rate. At best the WebM
On Jan 11, 2011, at 5:43 PM, Chris Pearce wrote:
On 12/01/2011 2:22 p.m., Dirk-Willem van Gulik wrote:
On 12 Jan 2011, at 01:17, Chris Pearce wrote:
I cannot think of a format where this would in fact be the case - but for
a few arcane ones like an animated push gif without a loop.
We can't have an API based on frame rate because at least in WebM, the
frame rate is just an informational piece of metadata that may not match
what's in the file and may not be there at all. Thus, the browser has no
way of exposing .framerate or anything like it.
For now, I suggest that
On Wed, 12 Jan 2011 03:16:35 +0100, Eric Carlson eric.carl...@apple.com
wrote:
On Jan 11, 2011, at 5:43 PM, Chris Pearce wrote:
On 12/01/2011 2:22 p.m., Dirk-Willem van Gulik wrote:
On 12 Jan 2011, at 01:17, Chris Pearce wrote:
I cannot think of a format where this would in fact be the
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