史蒂夫嘰嘰叫: 2月 2009

2009年2月24日星期二

popen and mmap

轉載

http://groups.google.com/group/comp.os.linux.development.system/browse_thread/thread/113038b65f4d3257

On Sat, 24 Jan 2009 12:32:40 -0800 (PST) spasmous2 <spasm...@gmail.com> wrote:
| I want to pipe the output of a system utility to a C program I'm
| writing. I tried popen() and it works nicely. The return type is a
| FILE* which I would like to map to memory using mmap() in the
| following way:
|
| file = popen(command,"r");
|
| data = (char*)mmap(NULL, size, PROT_READ, MAP_PRIVATE, fileno
| (file), 0);
|
| However the mmap command returns an error 'No such device', which I
| looked up to mean 'The fildes parameter does not refer to a *TYPE2
| stream file (*STMF) in the "root" (/), QOpenSys, or user-defined file
| systems.'
|
| I am unsure really what this means - do you know if it's a deal
| breaker or is there a solution?

You've been told by another followup that you cannot mmap a pipe. The reason
you cannot do this is because a pipe is not data storage that can be accessed
by random position. In an extreme way, a tape could be, but even it does not
work that way with existing drivers. A pipe is a _sequential_ data stream
produced by the writing of another program.

If you want random memory access to data from another program, what you want
is a shared mapping between these programs. There are a couple ways to do
that between processes. Or you could use threads (if willing to spend time
to understand the complexities of threads).

以上的意思是說mmap不能用在任何streaming的應用

殘念

2009年2月18日星期三

PXA255 uboot

patch uboot

+===================================================================
+--- u-boot-1.1.6.orig/board/pxa255_idp/memsetup.S
++++ u-boot-1.1.6/board/pxa255_idp/memsetup.S
+@@ -41,8 +41,8 @@ DRAM_SIZE:  .long   CFG_DRAM_SIZE
+ /*
+  * 	Memory setup
+  */
+-.globl memsetup
+-memsetup:
++.globl lowlevel_init
++lowlevel_init:
+ 
+ 	mov      r10, lr
+ 
+Index: u-boot-1.1.6/include/configs/pxa255_idp.h
+===================================================================
+--- u-boot-1.1.6.orig/include/configs/pxa255_idp.h
++++ u-boot-1.1.6/include/configs/pxa255_idp.h
+@@ -41,7 +41,7 @@
+  * If we are developing, we might want to start armboot from ram
+  * so we MUST NOT initialize critical regs like mem-timing ...
+  */
+-#define CONFIG_INIT_CRITICAL			/* undef for developing */
++#undef CONFIG_INIT_CRITICAL			/* undef for developing */
+ 
+ /*
+  * define the following to enable debug blinks.  A debug blink function
============================================================

CROSS_COMPILE=arm-linux-uclibc-

make pxa255_idp_config
make all

2009年2月16日星期一

mipsel linux mplayer

Download MPlayer-1.0rc2

偶只想要decoder,所以拿掉encoder

./configure --enable-cross-compile --target=mips-linux --cc=mipsel-linux-uclibc-gcc --host-cc=gcc --disable-mencoder

make

然後錯誤出現囉

修改libavutil/internal.h
加入以下function

#if !HAVE_LLRINT
static av_always_inline long long llrint(double x)
{
return rint(x);
}
#endif /* HAVE_LLRINT */

#if !HAVE_LRINT
static av_always_inline long int lrint(double x)
{
return rint(x);
}
#endif /* HAVE_LRINT */

#if !HAVE_ROUND
static av_always_inline double round(double x)
{
return (x > 0) ? floor(x + 0.5) : ceil(x - 0.5);
}
#endif /* HAVE_ROUND */

#if !HAVE_ROUNDF
static av_always_inline float roundf(float x)
{
return (x > 0) ? floor(x + 0.5) : ceil(x - 0.5);
}
#endif /* HAVE_ROUNDF */

#if !HAVE_TRUNCF
static av_always_inline float truncf(float x)
{
return (x > 0) ? floor(x) : ceil(x);
}
#endif /* HAVE_TRUNCF */

降樣子就OK囉

mipsel-linux-uclibc-strip mplayer

將mplayer丟到target上執行

video out to framebuffer & no sound
./mplayer -vo fbdev -nosound 0001.AVI

允許丟棄frame
./mplayer -vo fbdev -nosound -framedrop ./鐵鉆山老二-43.29.mpeg

rescale to 320x240 frame rate 5, -ni是在處理不正確的avi format
./mplayer -vf scale=320:240 -fps 5 -zoom -vo fbdev -nosound -ni ./luna.avi

./mplayer -vo fbdev -nosound ./32.70_0002.wmv

連WMV都可以play,真是讚啊

Internet radio
./mplayer -playlist ../tunein-station-4.pls

# ./mplayer -vo fbdev -nosound -framedrop 五分山20080921-小黑-Skorpion001.mpeg
MPlayer 1.0rc2-3.4.6 (C) 2000-2007 MPlayer Team
CPU: SGI MIPS

Playing 五分山20080921-小黑-Skorpion001.mpeg.
MPEG-PS file format detected.
VIDEO: MPEG1 352x240 (aspect 12) 29.970 fps 1152.0 kbps (144.0 kbyte/s)
==========================================================================
Opening video decoder: [mpegpes] MPEG 1/2 Video passthrough
VDec: vo config request - 352 x 240 (preferred colorspace: Mpeg PES)
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
The selected video_out device is incompatible with this codec.
Try appending the scale filter to your filter list,
e.g. -vf spp,scale instead of -vf spp.
VDecoder init failed :(
Opening video decoder: [libmpeg2] MPEG 1/2 Video decoder libmpeg2-v0.4.0b
Selected video codec: [mpeg12] vfm: libmpeg2 (MPEG-1 or 2 (libmpeg2))
==========================================================================
Audio: no sound
Starting playback...
VDec: vo config request - 352 x 240 (preferred colorspace: Planar YV12)
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.30:1 - prescaling to correct movie aspect.
[swscaler @ 0xaa7440]No accelerated colorspace conversion found
[swscaler @ 0xaa7440]SwScaler: using unscaled yuv420p -> bgr565 special converter
VO: [fbdev] 352x240 => 352x270 BGR 16-bit
V: 10.5 296/296 105% 74% 0.0% 0 0

如果使用libmad
執行時加上 -ac mad

Reference

http://amoi.it168.com/blog.php?tid=321580

http://www.oppo.com/index.php?q=oppoblog/view/11752

http://people.bath.ac.uk/enpsgp/floating_point.html

http://cha.homeip.net/blog/archives/2008/03/mplayerffmpeg.html

http://blog.chinaunix.net/u1/34961/showart_494026.html

2009年2月24日 星期二