UDMA test needed for high bit-rate h264

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Trammell Hudson

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Nov 28, 2010, 2:27:51 PM11/28/10
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Does anyone have a 5D and a UDMA card to test an exciting new
development? The attached build has a setting for qscale to control
the bit rate: the default is -8, which is ~45 Mbps. My non-UDMA
Sandisk Extreme III card can't handle -12 == 64 Mbps for more than a
few seconds before the buffer fills up. (It can, however, handle
qscale of +8 == 7 Mbps just fine... I see a trip to Adorama in my
near future.)

To adjust the bit rate, go to the "Debug" menu and click on the
qscale option. It will count down to -16 and then wrap to +16 so
you can try different settings. Note that this also switches the
camera into a fixed bit-rate setting instead of the default VBR.

--
Trammell

magiclantern-0.1.9.zip

PinkF_

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Nov 28, 2010, 3:04:18 PM11/28/10
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My card Pretec (32GB 233x) works fine to -13.
When set qscale -14, recording 3 seconds and stops
Sometimes at -14 works without a problem ... :)

Sean Simpson

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Nov 28, 2010, 3:15:48 PM11/28/10
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-14 and -15 were hitting around 58mb/s where the qscale -16 was hitting 78/79 for the second or two that it could handle.

-Sean

On Sun, Nov 28, 2010 at 3:14 PM, Sean Simpson <simpson.sm@gmail.com> wrote:
works on my SanDisk UDMA 60mb/s up to -14 and -15 where it is barely tolerable.  -16 is unusable as it breaches the 60mb/s max of my card.

-Sean



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Trammell Hudson

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Nov 28, 2010, 4:26:44 PM11/28/10
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On Sun, Nov 28, 2010 at 03:15:48PM -0500, Sean Simpson wrote:
> works on my SanDisk UDMA 60mb/s up to -14 and -15 where it is barely
> tolerable. -16 is unusable as it breaches the 60mb/s max of my card.

The cards are rated to 60 MB/s, while the video is only 60 Mb/s.
That factor of 8 should be plenty of overhead, although I have seen
many reports that the cards have far less bandwidth than "rated".

I have just purchased a Lexar 16 GB UDMA 400x card that is supposed
to be good for 60 MB/s as well. My results have been inconsistent
as to the maximum quality value it will support; sometimes -15
works consistently, but othertimes -13 fails.

Are you shooting 24, 25 or 30p? I did a quick test with -8 through
-16 and posted the results on the wiki:

http://magiclantern.wikia.com/wiki/Bit_rate

--
Trammell

Sean Simpson

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Nov 28, 2010, 11:42:36 PM11/28/10
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I was shooting 24p on Sandisk UDMA 60mb/s.

-Sean

Trammell

Gilbert M

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Nov 29, 2010, 12:14:46 AM11/29/10
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I am getting buffer bar at only at one block especially when I move the camera from left to right, back and forth. I was able to record for 2mins+ on -12 on qscale, the card is sandisk extreme III 30MB/s type, 4GB.



Gilbert M

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Nov 29, 2010, 12:28:37 AM11/29/10
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my patriot 16GB 266x chokes at -12 most of the time. Holds it own on -8.

Lars Steenhoff

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Nov 29, 2010, 6:31:00 AM11/29/10
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The bit-rate is always a little variable with h264, try recording with
the lenscap on and see how long you can record.
If there is less information to record the bitrate on the file will go
down. with a fast moving shot it will go up.

Gilbert M

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Nov 29, 2010, 2:56:12 PM11/29/10
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Are my emails going through? I am not receiving anything.

Deke Kincaid

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Nov 30, 2010, 2:08:28 AM11/30/10
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yes, all 3 came through.

-deke

Chris Barcellos

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Nov 30, 2010, 2:33:12 AM11/30/10
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I tried a bit different experiment tonight. Put camera on slider. I
shot three different clips, on with standard firmware, one with magic
lantern at -8 and one with ML at -12. I slid across a background in
focus of various printed cloth from my wife's sewing scraps. Now I
didn't get real strict as to exact timing and speed, but this is my
result. Results

Standard Firmware 42 sec ---> 237,326 5650
KB per second.
ML Set at -8 44 sec ---> 247,534 5625
kb per second.
ML Set at -12 36 sec ---> 153,011 4250
kb per second.

Seems like my test are reducing bit rate ?

By the way -15 crashed my 133x Kingston Elite Pro card
> > Trammell- Hide quoted text -
>
> - Show quoted text -

sato

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Dec 7, 2010, 11:22:51 AM12/7/10
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only one bar with two square fill at -16 with lexar 600x (90 mb/sec)
no buffer bar at -14

On 28 Nov, 20:27, Trammell Hudson <hud...@osresearch.net> wrote:

Moira O'Brien LIPF

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Dec 8, 2010, 7:59:37 AM12/8/10
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Having finished shooting for Christmas, I updated to 0.1.9 with the variable bit rates and have been trying it out this morning.  Using a Sandisk Extreme III 320 MB/s card I have only once had a cut out after a few seconds at -16.  On all other occasions at rates of -12 to -16 I achieved 30 seconds plus recording with no sign of buffer overflow.  On most of these recordings I used whip pans.

Moira

Moira O'Brien LIPF


Moira O'Brien LIPF

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Dec 9, 2010, 12:58:26 PM12/9/10
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I did some further testing at different ISOs and found significant differences in usable bit-rates:

ISO 6400    -10 OK, -11 failed
ISO 3200    -12 OK, I buffer mark, -13 fail
ISO 1600    -13 OK, -14 2 buffer marks, -15 6 secs only
ISO  640    -16 OK

All this on a 32MB/s Sandisk Extreme III.


Moira

Lars Steenhoff

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Dec 12, 2010, 7:37:41 PM12/12/10
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http://www.larssteenhoff.com/blog/?p=805

Here are the the results of my testings with the different qscale
settings.

Because the embedded vimeo clips are recompressed it will be harder to
see the difference, if you download the source files and apply a grade
the differences will become noticable.
All original files can be downloaded at the vimeo links.

The camera settings were:

ISO – 320
FPS 24

dreamlx

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Dec 28, 2010, 11:40:04 AM12/28/10
to Magic Lantern firmware development
First of all many thanks for this feature. It would be nice if this
setting would also be saved to configuration file.
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