Go to advanced search

by lb
Mon Oct 08, 2012 10:28 pm
Forum: Graphics, sound and multimedia
Topic: Volume control via a potentiometer
Replies: 4
Views: 2992

Re: Volume control via a potentiometer

Line outputs should have a relatively low impedance. Try 220-1K ohm, but I can't tell for sure if this will work well. Analog volume control is definitely better than using the software mixer, though. Reduced mixer volume is really bad for analog audio quality on the Pi! You should keep it at 100% a...
by lb
Mon Oct 08, 2012 5:00 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI driver latency and a possible solution
Replies: 242
Views: 152925

Re: SPI driver latency and a possible solution

The patch is unreadable - you messed up formatting of many files. Can you make a proper patch?
by lb
Tue Oct 02, 2012 12:11 pm
Forum: Deutsch
Topic: Welche SD-Karte?
Replies: 13
Views: 24543

Re: Welche SD-Karte?

Das Raspberry Pi unterstützt die neueren UHS-Transfermodi nicht, mit denen mehr als (theoretische) 25 MB/s möglich werden. Die Geschwindigkeit bei sequentiellen Zugriffen ist aber auch nicht der springende Punkt. Praktisch alle SD-Karten bieten hier ausreichende Performance. Der "Benchmark" mit hdpa...
by lb
Tue Oct 02, 2012 11:37 am
Forum: Troubleshooting
Topic: USB - the Elephant in our Room
Replies: 802
Views: 298154

Re: USB - the Elephant in our Room

It looks like you can't really rely on the Linux kernel having low latencies. I wonder if it would be sensible and/or possible to split up the USB driver into two parts. A low-level part that does all the timing-critical stuff and is executed entirely in FIQs, and a high-level part that runs as a re...
by lb
Thu Sep 20, 2012 4:42 pm
Forum: Troubleshooting
Topic: USB - the Elephant in our Room
Replies: 802
Views: 298154

Re: USB - the Elephant in our Room

obcd, have you tried the latest firmware and kernel? The output quality of the integrated analog output should be greatly improved! Usually, it shouldn't be a problem that the output is limited to about 11 bits - music doesn't have more than about 10 bits of dynamic range.
by lb
Sat Sep 08, 2012 11:36 pm
Forum: Raspberry Pi OS
Topic: [Project] Flash
Replies: 19
Views: 5496

Re: [Project] Flash

What features do you hope to receive that Gnash isn't providing you? I'm not hoping for anything. ;) Gnash simply does not work in a usable fashion at all with most Flash content, and this has been its state for years. Moreover, the Pi is simply too slow and restricted for most Flash content, and I...
by lb
Sat Sep 08, 2012 6:26 pm
Forum: Raspberry Pi OS
Topic: [Project] Flash
Replies: 19
Views: 5496

Re: [Project] Flash

You are using Gnash, which is not a usable replacement for Adobe Flash at all. Gnash only implements a fraction of Flash's features and is very buggy and slow. Furthermore, hardware-accelerated video decoding isn't implemented. We'll never have a Flash implementation on the Pi that works well. Just ...
by lb
Thu Sep 06, 2012 6:34 pm
Forum: Debian
Topic: ext4 file system
Replies: 12
Views: 17471

Re: ext4 file system

Generally, there are two types of wear leveling - dynamic and static. Dynamic wear leveling can only distribute wear among blocks that change (that's not ideal for a typical OS installation, since in this case many blocks never change). Static wear leveling makes sure to wear all blocks approximatel...
by lb
Tue Aug 21, 2012 2:30 am
Forum: Networking and servers
Topic: iptables does not close port
Replies: 8
Views: 6685

Re: iptables does not close port

iptables is a beast, but you can somewhat tame it with shorewall.

But seriously, why is there no pf port for Linux yet?
by lb
Thu Aug 16, 2012 8:42 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: ttyAMA0: 1 input overrun(s)
Replies: 17
Views: 10822

Re: ttyAMA0: 1 input overrun(s)

/sys/module/sdhci_bcm2708/parameters/missing_status says N, so the cmdline.txt options works. To make it even worse, I have also errors like Aug 15 13:00:38 raspberrypi kernel: [ 453.642572] mmc0: final write to SD card still running Aug 15 13:00:47 raspberrypi kernel: [ 463.499853] mmc0: Timeout w...
by lb
Thu Aug 16, 2012 8:35 pm
Forum: Deutsch
Topic: Raspberry Ende August bei Vesalia.de?
Replies: 12
Views: 4326

Re: Raspberry Ende August bei Vesalia.de?

Wo ist der Vorteil, wenn du im Supermarkt an der Kasse ein HDMI-Kabel kaufst? Du hast es direkt parat. Naja. Vesalia macht genau solche tollen Lieferversprechen wie Farnell oder RS. Ich würde da nicht meine Hand für ins Feuer legen, dass die Termine eingehalten werden. ;) Und Farnell hat im Moment ...
by lb
Thu Aug 16, 2012 4:15 pm
Forum: Deutsch
Topic: Raspberry Ende August bei Vesalia.de?
Replies: 12
Views: 4326

Re: Raspberry Ende August bei Vesalia.de?

40 EUR plus Versandkosten? Das erscheint mir aber arg teuer! Bei RS und Farnell habe ich inkl. Versandkosten knapp 38 EUR bezahlt, wenn ich mich recht erinnere. Was soll der Vorteil bei Vesalia sein?
by lb
Thu Aug 16, 2012 2:02 pm
Forum: OpenGLES
Topic: Texture Compression
Replies: 29
Views: 6792

Re: Texture Compression

Well, a 2D plane/sprite renderer is really simple to do with ES 2.0, there is none of the somewhat complex transformation math involved, and you can easily apply various effects to the sprites with a fragment shader. ARM's Mali Development Center has some nice examples, including conversion tools. T...
by lb
Thu Aug 16, 2012 10:48 am
Forum: OpenGLES
Topic: Texture Compression
Replies: 29
Views: 6792

Re: Texture Compression

Again, what speaks against the easy solution of using a separate texture for alpha? This uses less than 16 bits per pixel, but provides better quality and full alpha.
by lb
Tue Aug 14, 2012 12:13 pm
Forum: OpenGLES
Topic: Texture Compression
Replies: 29
Views: 6792

Re: Texture Compression

Well, the 4444 format has quite horrible quality... I cannot recommend it at all. What's your use-case?
by lb
Sun Aug 12, 2012 11:32 pm
Forum: OpenGLES
Topic: Texture Compression
Replies: 29
Views: 6792

Re: Texture Compression

For the love of all that is good, please use OpenGL ES 2.0. ETC1 compression is supported. Edit: sorry, I did not notice you want compressed RGB A textures. ETC1 does not support alpha. But you can use an ETC1 compressed RGB8 texture and store alpha in a separate A8 texture. It's easy to combine bot...
by lb
Sat Aug 11, 2012 12:43 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: ttyAMA0: 1 input overrun(s)
Replies: 17
Views: 10822

Re: ttyAMA0: 1 input overrun(s)

Please try to add sdhci-bcm2708.missing_status=0 to cmdline.txt. Unfortunately this won't work well with all SD cards, but it reduces interrupt latency and should avoid the overruns.
by lb
Thu Aug 09, 2012 9:04 pm
Forum: Networking and servers
Topic: sdcard server unrealistic?
Replies: 11
Views: 3266

Re: sdcard server unrealistic?

In my experience, EXT4 is quite reliable with journaling enabled, but the SD card's controller might not deal well with unexpected power outages. However, you can disable journaling with tune2fs, and doing so reduces writes and speeds up operation considerably, possibly at the cost of reliability.
by lb
Tue Aug 07, 2012 1:14 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SMTH08I - I2C kernel module
Replies: 8
Views: 2378

Re: SMTH08I - I2C kernel module

The GPIO on the Pi is definitely NOT 5V tolerant. The examples on that page are potentially dangerous for your Pi!

Use something like this for both SDA and SCL.
by lb
Tue Aug 07, 2012 12:51 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: GPIO precision timing (with minimal cost)
Replies: 12
Views: 4910

Re: GPIO precision timing (with minimal cost)

Use a microcontroller. A small Atmel AVR (e.g. Tiny2313) only costs 1-2$ and is up to the job, easy to program and provides a lot of flexibility.
by lb
Mon Aug 06, 2012 7:17 pm
Forum: Graphics programming
Topic: GTK+ Toolkit?
Replies: 23
Views: 15036

Re: GTK+ Toolkit?

I can only recommend to use GTK (with the excellent PyGTK bindings) directly instead. wx is badly designed, badly documented, buggy and a lot of bloat. The Python bindings are a mess, too.

I've used a lot of UI toolkits, and wx is about the worst I've seen yet.
by lb
Sun Aug 05, 2012 1:10 pm
Forum: Troubleshooting
Topic: USB - the Elephant in our Room
Replies: 802
Views: 298154

Re: USB - the Elephant in our Room

Theq FIQ solution seems to be more worthwile. There are other possible sources of interrupt latency than the SDHCI driver, and reducing IRQ overhead is a good thing, too.
by lb
Sun Aug 05, 2012 2:11 am
Forum: Advanced users
Topic: Minimum FAT partition size?
Replies: 9
Views: 6502

Re: Minimum FAT partition size?

CapnBry wrote:A loopback filesystem doesn't make anything smaller
No, but it allows you to workaround partition size issues, and makes installation dead-easy (just copy files with whatever method you have, no image writing necessary).
by lb
Sat Aug 04, 2012 1:54 pm
Forum: Advanced users
Topic: Minimum FAT partition size?
Replies: 9
Views: 6502

Re: Minimum FAT partition size?

I think a loopback filesystem (similar to Ubuntu's WUBI) is the way to go if you want to keep everything as small as possible. But I don't understand your bandwidth issue. Why don't you compress the SD card image?
by lb
Thu Aug 02, 2012 12:59 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: How fast is GPIO??
Replies: 9
Views: 4357

Re: How fast is GPIO??

Carefully written kernel code definitely should be good enough for many tasks that need precise timing, and with interrupts that can be quite efficient. It's probably easier than switching to a real-time OS that is overall badly supported.

Go to advanced search