[FFmpeg-devel] Fwd: framebuffer device demuxer

[Diego Biurrun]

On Tue, Jan 25, 2011 at 11:47:35PM +0100, Stefano Sabatini wrote:
> 
> Not yet for commit, I want to clean it up still a bit (and maybe add
> some more features), review is welcome of course.
> 
> --- a/configure
> +++ b/configure
> @@ -2850,6 +2851,7 @@ fi
>  
>  check_header linux/videodev.h
>  check_header linux/videodev2.h
> +check_header linux/fb.h
>  check_header sys/videoio.h

alphabetical order

> --- a/doc/indevs.texi
> +++ b/doc/indevs.texi
> @@ -59,6 +59,16 @@ BSD video input device.
>  
>  Linux DV 1394 input device.
>  
> + at section framebuffer
> +
> +Linux frame buffer input device.

framebuffer

> +For example, to record from the frame buffer device /dev/fb0 with

ditto

> --- /dev/null
> +++ b/libavdevice/framebuffer.c
> @@ -0,0 +1,220 @@
> +
> +/**
> + * @file
> + * Linux Frame Buffer input device

framebuffer

> + * Based on code from fbgrab.c by Gunnar Monell.

What license was that code?

> +#define DEBUG
> +
> +#include <unistd.h>
> +#include <fcntl.h>
> +#include <sys/ioctl.h>
> +#include <sys/time.h>
> +#include <sys/mman.h>
> +#include <time.h>
> +#include <linux/fb.h>
> +#include "libavutil/mem.h"

extra good karma for an empty line between local and system headers

> +#include "libavutil/pixdesc.h"
> +#include "libavformat/avformat.h"
> +#define _LINUX_TIME_H 1

Where does this #define have an effect if you place it after #includes?

> +av_cold static int frame_buffer_read_header(AVFormatContext *avctx, AVFormatParameters *ap)
> +{
> +    struct fb_var_screeninfo fb_varinfo;
> +
> +    memset(&fb_varinfo, 0, sizeof(struct fb_var_screeninfo));

Is the nulling necessary?  Simpler should be

  struct fb_var_screeninfo fb_varinfo = { 0 };

> +    if (ioctl(fb_ctx->fd, FBIOGET_VSCREENINFO, &fb_varinfo) < 0){
> +
> +    if (ioctl(fb_ctx->fd, FBIOGET_FSCREENINFO, &fb_fixinfo) < 0){

) {

> +    fb_ctx->frame_size = fb_varinfo.xres * fb_varinfo.yres * ((bits_per_pixel+7)>>3);
> +    fb_ctx->linesize = fb_varinfo.xres * ((bits_per_pixel+7)>>3);
> +    fb_ctx->frame_linesize = fb_fixinfo.line_length;
> +    fb_ctx->time_base  = ap->time_base;
> +    fb_ctx->time_frame = av_gettime() / av_q2d(ap->time_base); /* timestamp in time_base unit */
> +    fb_ctx->data = mmap(NULL, fb_fixinfo.line_length * fb_varinfo.yres, PROT_READ, MAP_SHARED, fb_ctx->fd, 0);

Vertical alignment and spaces around operators could make this more
readable.

> +AVInputFormat framebuffer_demuxer = {
> +    .name           = "framebuffer",
> +    .long_name      = NULL_IF_CONFIG_SMALL("Linux Frame Buffer"),

framebuffer

Diego