[FFmpeg-devel] Fwd: framebuffer device demuxer
Måns Rullgård
mans
Fri Jan 28 17:32:38 CET 2011
Stefano Sabatini <stefano.sabatini-lala at poste.it> writes:
> On date Friday 2011-01-28 01:10:46 +0000, M?ns Rullg?rd encoded:
>
>> I think "framebuffer" is a bit too generic a name. After all,
>> anything with a display of any kind has a framebuffer. The Linux
>> framebuffer device generally goes by the name "fbdev", so perhaps that
>> would be a better name.
>
> Replaced with linuxfb, this should be more explicative of the fact
> that it is a linux thing, this should prevent having users ask "I'm on
> windows, why can't I find the fbdev device?".
Works for me.
>> > + if ((fb->fd = open(avctx->filename, flags)) == -1) {
>> > + ret = AVERROR(errno);
>> > + av_log(avctx, AV_LOG_ERROR, "Could not open framebuffer device '%s'.\n", avctx->filename);
>> > + goto fail;
>>
>> You could return directly here and drop the check before close().
>
> Done.
Not exactly...
>> > + fb->width = fb_varinfo.xres;
>> > + fb->height = fb_varinfo.yres;
>> > + bits_per_pixel = fb_varinfo.bits_per_pixel;
>> > +
>> > + switch (bits_per_pixel) {
>> > + case 8: pix_fmt = PIX_FMT_PAL8 ; break;
>> > + case 15: pix_fmt = PIX_FMT_BGR555; break;
>> > + case 16: pix_fmt = PIX_FMT_RGB565; break;
>> > + case 24: pix_fmt = PIX_FMT_RGB24 ; break;
>> > + case 32: pix_fmt = PIX_FMT_RGB32 ; break;
>> > + default:
>> > + ret = AVERROR(EINVAL);
>> > + av_log(avctx, AV_LOG_ERROR, "Image with bits per pixel depth %d not supported.\n",
>> > + bits_per_pixel);
>> > + goto fail;
>> > + }
>>
>> These are not the only formats possible. You cannot use bits per
>> pixel exclusively to determine the format.
>
> Yes indeed. I'm using a far more robust solution now, yet incomplete,
> also I have to see how to handle pal formats.
There is also the issue of driver-specific formats, but let's ignore
those for now.
>> > +AVInputFormat framebuffer_demuxer = {
>> > + .name = "framebuffer",
>> > + .long_name = NULL_IF_CONFIG_SMALL("Linux framebuffer"),
>> > + .priv_data_size = sizeof(FrameBufferContext),
>> > + .read_header = framebuffer_read_header,
>> > + .read_packet = framebuffer_read_packet,
>> > + .read_close = framebuffer_read_close,
>> > + .flags = AVFMT_NOFILE,
>> > +};
>>
>> Is AVFMT_NOFILE really correct here? I'm not sure what its semantics
>> are supposed to be.
>
> It's not explained in the docs, but AVFMT_NOFILE is used for all the
> input and output device (possibly is what distinguishes a device from
> a muxer/demuxer).
OK, that's a reasonable explanation. Perhaps it should be documented
somewhere.
> And I'm still observing the 100% CPU problem noted by Luca A. in this
> thread,
That needs to be resolved, obviously.
> a 0-memcpy solution is possible but it requires some change to the
> framework (as the written packet contains aligned data, which is not
> supported ATM).
I don't think a zero-copy is a good idea here. The framebuffer is
likely to be updated while encoding is in progress.
> @@ -2863,6 +2864,33 @@ fi
>
> texi2html -version > /dev/null 2>&1 && enable texi2html || disable texi2html
>
> +if enabled network; then
> + check_type "sys/types.h sys/socket.h" socklen_t
> + check_type netdb.h "struct addrinfo"
> + check_type netinet/in.h "struct ipv6_mreq" -D_DARWIN_C_SOURCE
> + check_type netinet/in.h "struct sockaddr_in6"
> + check_type "sys/types.h sys/socket.h" "struct sockaddr_storage"
> + check_struct "sys/types.h sys/socket.h" "struct sockaddr" sa_len
> + # Prefer arpa/inet.h over winsock2
> + if check_header arpa/inet.h ; then
> + check_func closesocket
> + elif check_header winsock2.h ; then
> + check_func_headers winsock2.h closesocket -lws2 && \
> + network_extralibs="-lws2" || \
> + { check_func_headers winsock2.h closesocket -lws2_32 && \
> + network_extralibs="-lws2_32"; }
> + check_type ws2tcpip.h socklen_t
> + check_type ws2tcpip.h "struct addrinfo"
> + check_type ws2tcpip.h "struct ipv6_mreq"
> + check_type ws2tcpip.h "struct sockaddr_in6"
> + check_type ws2tcpip.h "struct sockaddr_storage"
> + check_struct winsock2.h "struct sockaddr" sa_len
> + else
> + disable network
> + fi
> +fi
Bad merge? This chunk was moved up a while ago.
> +check_header linux/fb.h
> check_header linux/videodev.h
> check_header linux/videodev2.h
> check_header sys/videoio.h
[...]
> diff --git a/libavdevice/linuxfb.c b/libavdevice/linuxfb.c
> new file mode 100644
> index 0000000..e174edf
> --- /dev/null
> +++ b/libavdevice/linuxfb.c
> @@ -0,0 +1,234 @@
> +/*
> + * 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.
> + */
> +
> +#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)
Please change the argument to a pointer.
> +{
> + int i;
> +
> + for (i = 0; i < FF_ARRAY_ELEMS(rgb_pixfmt_map); i++) {
> + struct rgb_pixfmt_map_entry entry = rgb_pixfmt_map[i];
Please use a pointer here.
> + 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; ///< current time
> +
> + 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);
> +
> + if (avctx->flags & AVFMT_FLAG_NONBLOCK)
> + flags |= O_NONBLOCK;
> +
> + 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));
> + close(fb->fd);
Err... that should be "return ret", not close().
> + }
> +
> + 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;
> + }
> +
> + if (ap->time_base.den <= 0) {
> + ret = AVERROR(EINVAL);
> + av_log(avctx, AV_LOG_ERROR, "Invalid time base %d/%d\n", ap->time_base.num, ap->time_base.den);
> + goto fail;
> + }
> +
> + av_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in microseconds */
> +
> + 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, "Image with bits per pixel depth %d not supported.\n",
> + fb_varinfo.bits_per_pixel);
This error message doesn't quite match the error condition. I'd go
with something like "Framebuffer pixel format not supported".
> + 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_gettime() / av_q2d(ap->time_base);
Don't initialise time_frame to current time. There could be any delay
between init and first capture. Set it to something invalid instead,
and check it in read_packet().
> + fb->data = mmap(NULL, fb_fixinfo.line_length * (fb_varinfo.yres + fb_varinfo.yoffset),
> + PROT_READ, MAP_SHARED, fb->fd, 0);
> + fb->visible_data = fb->data +
> + (fb_varinfo.xoffset + fb_varinfo.xres_virtual * fb_varinfo.yoffset) * bytes_per_pixel;
This can change at any time if an application reconfigures the
framebuffer. I'm not sure, but I think this also happens
automatically when the text console scrolls.
> + if (fb->data == MAP_FAILED) {
> + ret = AVERROR(errno);
> + av_log(avctx, AV_LOG_ERROR, "Error in mmap(): %s\n", strerror(errno));
> + goto fail;
> + }
> +
> + 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:
> + if (fb->fd >= 0)
> + close(fb->fd);
Fix the open() check above and remove this if().
> + 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;
> +
> + /* wait based on the frame rate */
> + while (1) {
> + curtime = av_gettime();
> + delay = curtime - fb->time_frame * av_q2d(fb->time_base);
> + 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 is asking for a negative delay. That's probably the cause of the
CPU hogging.
> + }
> +
> + 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
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