[FFmpeg-devel] Fwd: framebuffer device demuxer

Måns Rullgård mans
Sun Jan 30 17:36:38 CET 2011


Stefano Sabatini <stefano.sabatini-lala at poste.it> writes:

> diff --git a/libavdevice/linuxfb.c b/libavdevice/linuxfb.c
> new file mode 100644
> index 0000000..71fa653
> --- /dev/null
> +++ b/libavdevice/linuxfb.c
> @@ -0,0 +1,240 @@
> +/*
> + * Copyright (c) 2010 Stefano Sabatini
> + * Copyright (c) 2009 Giliard B. de Freitas <giliarde at gmail.com>
> + * Copyright (C) 2002 Gunnar Monell <gmo at linux.nu>
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +/**
> + * @file
> + * Linux framebuffer input device,
> + * inspired by code from fbgrab.c by Gunnar Monell.
> + */
> +
> +/* #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"
> +#include "libavutil/pixdesc.h"
> +#include "libavformat/avformat.h"
> +
> +struct rgb_pixfmt_map_entry {
> +    int bits_per_pixel;
> +    int red_offset, green_offset, blue_offset, alpha_offset;
> +    enum PixelFormat pixfmt;
> +};
> +
> +static struct rgb_pixfmt_map_entry rgb_pixfmt_map[] = {
> +    // bpp, r_offset,  g_offset, b_offset, a_offset, pixfmt
> +    {  32,   0,         8,       16,       24,       PIX_FMT_RGBA  },
> +    {  32,  16,         8,        0,       24,       PIX_FMT_BGRA  },
> +    {  32,   8,        16,       24,        0,       PIX_FMT_ARGB  },
> +    {  32,   3,         2,        8,        0,       PIX_FMT_ABGR  },
> +    {  24,   0,         8,       16,        0,       PIX_FMT_RGB24 },
> +    {  24,  16,         8,        0,        0,       PIX_FMT_BGR24 },
> +};
> +
> +static enum PixelFormat get_pixfmt_from_fb_varinfo(struct fb_var_screeninfo *varinfo)
> +{
> +    int i;
> +
> +    for (i = 0; i < FF_ARRAY_ELEMS(rgb_pixfmt_map); i++) {
> +        struct rgb_pixfmt_map_entry *entry = &rgb_pixfmt_map[i];
> +        if (entry->bits_per_pixel == varinfo->bits_per_pixel &&
> +            entry->red_offset     == varinfo->red.offset     &&
> +            entry->green_offset   == varinfo->green.offset   &&
> +            entry->blue_offset    == varinfo->blue.offset)
> +            return entry->pixfmt;
> +    }
> +
> +    return PIX_FMT_NONE;
> +}
> +
> +typedef struct {
> +    int frame_size;          ///< size in bytes of a grabbed frame
> +    AVRational time_base;    ///< time base
> +    int64_t time_frame;      ///< time for the next frame to output (in 1/1000000 units)
> +
> +    int frame_linesize;      ///< linesize of the output frame
> +    int linesize;            ///< linesize of the read framebuffer
> +    int height;              ///< height of the grab frame
> +    int width;               ///< width of the grab frame
> +    int fd;                  ///< framebuffer device file descriptor
> +
> +    uint8_t *data;           ///< framebuffer data
> +    uint8_t *visible_data;   ///< framebuffer visible data
> +} FrameBufferContext;
> +
> +av_cold static int linuxfb_read_header(AVFormatContext *avctx, AVFormatParameters *ap)
> +{
> +    FrameBufferContext *fb = avctx->priv_data;
> +    struct fb_var_screeninfo fb_varinfo;
> +    struct fb_fix_screeninfo fb_fixinfo;
> +    AVStream *st = NULL;
> +    enum PixelFormat pix_fmt;
> +    int ret, bytes_per_pixel, flags = O_RDONLY;
> +
> +    if (!(st = av_new_stream(avctx, 0)))
> +        return AVERROR(ENOMEM);
> +    av_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in microseconds */
> +
> +    if (ap->time_base.den <= 0) {
> +        av_log(avctx, AV_LOG_ERROR, "Invalid time base %d/%d\n", ap->time_base.num, ap->time_base.den);
> +        return AVERROR(EINVAL);
> +    }
> +
> +    if (avctx->flags & AVFMT_FLAG_NONBLOCK)
> +        flags |= O_NONBLOCK;

Come to think of it, O_NONBLOCK doesn't make sense on fbdev.  AFAICT
it is ignored by the drivers.

> +    if ((fb->fd = open(avctx->filename, flags)) == -1) {
> +        ret = AVERROR(errno);
> +        av_log(avctx, AV_LOG_ERROR, "Could not open framebuffer device '%s': %s\n",
> +               avctx->filename, strerror(ret));
> +        return ret;
> +    }
> +
> +    if (ioctl(fb->fd, FBIOGET_VSCREENINFO, &fb_varinfo) < 0) {
> +        ret = AVERROR(errno);
> +        av_log(avctx, AV_LOG_ERROR, "FBIOGET_VSCREENINFO: %s\n", strerror(errno));
> +        goto fail;
> +    }
> +
> +    if (ioctl(fb->fd, FBIOGET_FSCREENINFO, &fb_fixinfo) < 0) {
> +        ret = AVERROR(errno);
> +        av_log(avctx, AV_LOG_ERROR, "FBIOGET_FSCREENINFO: %s\n", strerror(errno));
> +        goto fail;
> +    }
> +
> +    fb->width  = fb_varinfo.xres;
> +    fb->height = fb_varinfo.yres;
> +
> +    pix_fmt = get_pixfmt_from_fb_varinfo(&fb_varinfo);
> +    if (pix_fmt == PIX_FMT_NONE) {
> +        ret = AVERROR(EINVAL);
> +        av_log(avctx, AV_LOG_ERROR, "Framebuffer pixel format not supported.\n");
> +        goto fail;
> +    }
> +
> +    bytes_per_pixel    = (fb_varinfo.bits_per_pixel + 7) >> 3;
> +    fb->frame_linesize = fb_varinfo.xres * bytes_per_pixel;
> +    fb->frame_size     = fb->frame_linesize * fb_varinfo.yres;
> +    fb->linesize       = fb_fixinfo.line_length;
> +    fb->time_base      = ap->time_base;
> +    fb->time_frame     = AV_NOPTS_VALUE;
> +    fb->data = mmap(NULL, fb_fixinfo.line_length * (fb_varinfo.yoffset + fb_varinfo.yres),
> +                    PROT_READ, MAP_SHARED, fb->fd, 0);
> +    if (fb->data == MAP_FAILED) {
> +        ret = AVERROR(errno);
> +        av_log(avctx, AV_LOG_ERROR, "Error in mmap(): %s\n", strerror(errno));
> +        goto fail;
> +    }
> +
> +    fb->visible_data = fb->data +
> +        (fb_varinfo.xoffset + fb_fixinfo.line_length * fb_varinfo.yoffset) * bytes_per_pixel;

You should mmap the entire framebuffer memory (as and query the current
display offset in read_packet().  Yes, I know you said it wasn't ready.

> +    st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
> +    st->codec->codec_id   = CODEC_ID_RAWVIDEO;
> +    st->codec->width      = fb->width;
> +    st->codec->height     = fb->height;
> +    st->codec->pix_fmt    = pix_fmt;
> +    st->codec->time_base  = ap->time_base;
> +    st->codec->bit_rate   = fb->frame_size / av_q2d(ap->time_base) * 8;
> +
> +    av_log(avctx, AV_LOG_INFO, "w:%d h:%d bpp:%d pixfmt:%s tb:%d/%d bit_rate:%d\n",
> +           fb->width, fb->height, fb_varinfo.bits_per_pixel,
> +           av_pix_fmt_descriptors[pix_fmt].name, ap->time_base.num, ap->time_base.den,
> +           st->codec->bit_rate);
> +    return 0;
> +
> +fail:
> +    close(fb->fd);
> +    return ret;
> +}
> +
> +static int linuxfb_read_packet(AVFormatContext *avctx, AVPacket *pkt)
> +{
> +    FrameBufferContext *fb = avctx->priv_data;
> +    int64_t curtime, delay;
> +    struct timespec ts;
> +    int i, ret;
> +    uint8_t *pin, *pout;
> +
> +    if (fb->time_frame == AV_NOPTS_VALUE)
> +        fb->time_frame = av_gettime();
> +
> +    /* wait based on the frame rate */
> +    while (1) {
> +        curtime = av_gettime();
> +        delay = fb->time_frame - curtime;
> +#ifdef DEBUG
> +        av_log(avctx, AV_LOG_DEBUG,
> +               "time_frame:%"PRId64" curtime:%"PRId64" delay:%"PRId64"\n",
> +               fb->time_frame, curtime, delay);
> +#endif

av_dlog()

> +        if (delay <= 0) {
> +            fb->time_frame += INT64_C(1000000) * av_q2d(fb->time_base);
> +            break;
> +        }
> +        if (avctx->flags & AVFMT_FLAG_NONBLOCK)
> +            return AVERROR(EAGAIN);
> +        ts.tv_sec  =  delay / 1000000;
> +        ts.tv_nsec = (delay % 1000000) * 1000;
> +        nanosleep(&ts, NULL);
> +    }

This loop is weird.  The correct way is something like this:

ts = delay; /* details omitted */
while (nanosleep(&ts, &ts) && errno == EINTR);

> +    if ((ret = av_new_packet(pkt, fb->frame_size)) < 0)
> +        return ret;
> +
> +    pkt->pts = curtime;
> +    pin  = fb->visible_data;
> +    pout = pkt->data;
> +
> +    for (i = 0; i < fb->height; i++) {
> +        memcpy(pout, pin, fb->frame_linesize);
> +        pin  += fb->linesize;
> +        pout += fb->frame_linesize;
> +    }
> +
> +    return fb->frame_size;
> +}
> +
> +av_cold static int linuxfb_read_close(AVFormatContext *avctx)
> +{
> +    FrameBufferContext *fb = avctx->priv_data;
> +
> +    munmap(fb->data, fb->frame_size);
> +    close(fb->fd);
> +
> +    return 0;
> +}
> +
> +AVInputFormat ff_linuxfb_demuxer = {
> +    .name           = "linuxfb",
> +    .long_name      = NULL_IF_CONFIG_SMALL("Linux framebuffer"),
> +    .priv_data_size = sizeof(FrameBufferContext),
> +    .read_header    = linuxfb_read_header,
> +    .read_packet    = linuxfb_read_packet,
> +    .read_close     = linuxfb_read_close,
> +    .flags          = AVFMT_NOFILE,
> +};
> -- 
> 1.7.2.3
>
>

-- 
M?ns Rullg?rd
mans at mansr.com



More information about the ffmpeg-devel mailing list