FFmpeg4/libavdevice/fbdev_common.c

/*
 * Copyright (c) 2011 Stefano Sabatini
 * Copyright (c) 2009 Giliard B. de Freitas <giliarde@gmail.com>
 * Copyright (C) 2002 Gunnar Monell <gmo@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
 */

#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include "fbdev_common.h"
#include "libavutil/common.h"
#include "avdevice.h"

struct rgb_pixfmt_map_entry {
    int bits_per_pixel;
    int red_offset, green_offset, blue_offset, alpha_offset;
    enum AVPixelFormat pixfmt;
};

static const struct rgb_pixfmt_map_entry rgb_pixfmt_map[] = {
    // bpp, red_offset,  green_offset, blue_offset, alpha_offset, pixfmt
    {  32,       0,           8,          16,           24,   AV_PIX_FMT_RGBA  },
    {  32,      16,           8,           0,           24,   AV_PIX_FMT_BGRA  },
    {  32,       8,          16,          24,            0,   AV_PIX_FMT_ARGB  },
    {  32,       3,           2,           8,            0,   AV_PIX_FMT_ABGR  },
    {  24,       0,           8,          16,            0,   AV_PIX_FMT_RGB24 },
    {  24,      16,           8,           0,            0,   AV_PIX_FMT_BGR24 },
    {  16,      11,           5,           0,            0,   AV_PIX_FMT_RGB565 },
};

enum AVPixelFormat ff_get_pixfmt_from_fb_varinfo(struct fb_var_screeninfo *varinfo)
{
    int i;

    for (i = 0; i < FF_ARRAY_ELEMS(rgb_pixfmt_map); i++) {
        const 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 AV_PIX_FMT_NONE;
}

const char* ff_fbdev_default_device()
{
    const char *dev = getenv("FRAMEBUFFER");
    if (!dev)
        dev = "/dev/fb0";
    return dev;
}

int ff_fbdev_get_device_list(AVDeviceInfoList *device_list)
{
    struct fb_var_screeninfo varinfo;
    struct fb_fix_screeninfo fixinfo;
    char device_file[12];
    AVDeviceInfo *device = NULL;
    int i, fd, ret = 0;
    const char *default_device = ff_fbdev_default_device();

    if (!device_list)
        return AVERROR(EINVAL);

    for (i = 0; i <= 31; i++) {
        snprintf(device_file, sizeof(device_file), "/dev/fb%d", i);

        if ((fd = avpriv_open(device_file, O_RDWR)) < 0) {
            int err = AVERROR(errno);
            if (err != AVERROR(ENOENT))
                av_log(NULL, AV_LOG_ERROR, "Could not open framebuffer device '%s': %s\n",
                       device_file, av_err2str(err));
            continue;
        }
        if (ioctl(fd, FBIOGET_VSCREENINFO, &varinfo) == -1)
            goto fail_device;
        if (ioctl(fd, FBIOGET_FSCREENINFO, &fixinfo) == -1)
            goto fail_device;

        device = av_mallocz(sizeof(AVDeviceInfo));
        if (!device) {
            ret = AVERROR(ENOMEM);
            goto fail_device;
        }
        device->device_name = av_strdup(device_file);
        device->device_description = av_strdup(fixinfo.id);
        if (!device->device_name || !device->device_description) {
            ret = AVERROR(ENOMEM);
            goto fail_device;
        }

        if ((ret = av_dynarray_add_nofree(&device_list->devices,
                                          &device_list->nb_devices, device)) < 0)
            goto fail_device;

        if (default_device && !strcmp(device->device_name, default_device)) {
            device_list->default_device = device_list->nb_devices - 1;
            default_device = NULL;
        }
        close(fd);
        continue;

      fail_device:
        if (device) {
            av_freep(&device->device_name);
            av_freep(&device->device_description);
            av_freep(&device);
        }
        if (fd >= 0)
            close(fd);
        if (ret < 0)
            return ret;
    }
    return 0;
}