libavdevice/vfwcap.c - vendor/opensource/ffmpeg - Git at Google

 /*
  * VFW capture interface
  * Copyright (c) 2006-2008 Ramiro Polla
  *
  * 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 "libavformat/avformat.h"
 #include <windows.h>
 #include <vfw.h>

 //#define DEBUG_VFW

 /* Defines for VFW missing from MinGW.
  * Remove this when MinGW incorporates them. */
 #define HWND_MESSAGE                ((HWND)-3)

 #define BI_RGB                      0

 /* End of missing MinGW defines */

 struct vfw_ctx {
     HWND hwnd;
     HANDLE mutex;
     HANDLE event;
     AVPacketList *pktl;
     AVFormatContext *s;
     unsigned int curbufsize;
     unsigned int frame_num;
 };

 static enum PixelFormat vfw_pixfmt(DWORD biCompression, WORD biBitCount)
 {
     switch(biCompression) {
     case MKTAG('Y', 'U', 'Y', '2'):
         return PIX_FMT_YUYV422;
     case MKTAG('I', '4', '2', '0'):
         return PIX_FMT_YUV420P;
     case BI_RGB:
         switch(biBitCount) { /* 1-8 are untested */
             case 1:
                 return PIX_FMT_MONOWHITE;
             case 4:
                 return PIX_FMT_RGB4;
             case 8:
                 return PIX_FMT_RGB8;
             case 16:
                 return PIX_FMT_RGB555;
             case 24:
                 return PIX_FMT_BGR24;
             case 32:
                 return PIX_FMT_RGB32;
         }
     }
     return -1;
 }

 #define dstruct(pctx, sname, var, type) \
     av_log(pctx, AV_LOG_DEBUG, #var":\t%"type"\n", sname->var)

 static void dump_captureparms(AVFormatContext *s, CAPTUREPARMS *cparms)
 {
     av_log(s, AV_LOG_DEBUG, "CAPTUREPARMS\n");
     dstruct(s, cparms, dwRequestMicroSecPerFrame, "lu");
     dstruct(s, cparms, fMakeUserHitOKToCapture, "d");
     dstruct(s, cparms, wPercentDropForError, "u");
     dstruct(s, cparms, fYield, "d");
     dstruct(s, cparms, dwIndexSize, "lu");
     dstruct(s, cparms, wChunkGranularity, "u");
     dstruct(s, cparms, fUsingDOSMemory, "d");
     dstruct(s, cparms, wNumVideoRequested, "u");
     dstruct(s, cparms, fCaptureAudio, "d");
     dstruct(s, cparms, wNumAudioRequested, "u");
     dstruct(s, cparms, vKeyAbort, "u");
     dstruct(s, cparms, fAbortLeftMouse, "d");
     dstruct(s, cparms, fAbortRightMouse, "d");
     dstruct(s, cparms, fLimitEnabled, "d");
     dstruct(s, cparms, wTimeLimit, "u");
     dstruct(s, cparms, fMCIControl, "d");
     dstruct(s, cparms, fStepMCIDevice, "d");
     dstruct(s, cparms, dwMCIStartTime, "lu");
     dstruct(s, cparms, dwMCIStopTime, "lu");
     dstruct(s, cparms, fStepCaptureAt2x, "d");
     dstruct(s, cparms, wStepCaptureAverageFrames, "u");
     dstruct(s, cparms, dwAudioBufferSize, "lu");
     dstruct(s, cparms, fDisableWriteCache, "d");
     dstruct(s, cparms, AVStreamMaster, "u");
 }

 static void dump_videohdr(AVFormatContext *s, VIDEOHDR *vhdr)
 {
 #ifdef DEBUG_VFW
     av_log(s, AV_LOG_DEBUG, "VIDEOHDR\n");
     dstruct(s, vhdr, lpData, "p");
     dstruct(s, vhdr, dwBufferLength, "lu");
     dstruct(s, vhdr, dwBytesUsed, "lu");
     dstruct(s, vhdr, dwTimeCaptured, "lu");
     dstruct(s, vhdr, dwUser, "lu");
     dstruct(s, vhdr, dwFlags, "lu");
     dstruct(s, vhdr, dwReserved[0], "lu");
     dstruct(s, vhdr, dwReserved[1], "lu");
     dstruct(s, vhdr, dwReserved[2], "lu");
     dstruct(s, vhdr, dwReserved[3], "lu");
 #endif
 }

 static void dump_bih(AVFormatContext *s, BITMAPINFOHEADER *bih)
 {
     av_log(s, AV_LOG_DEBUG, "BITMAPINFOHEADER\n");
     dstruct(s, bih, biSize, "lu");
     dstruct(s, bih, biWidth, "ld");
     dstruct(s, bih, biHeight, "ld");
     dstruct(s, bih, biPlanes, "d");
     dstruct(s, bih, biBitCount, "d");
     dstruct(s, bih, biCompression, "lu");
     av_log(s, AV_LOG_DEBUG, "    biCompression:\t\"%.4s\"\n",
                    (char*) &bih->biCompression);
     dstruct(s, bih, biSizeImage, "lu");
     dstruct(s, bih, biXPelsPerMeter, "lu");
     dstruct(s, bih, biYPelsPerMeter, "lu");
     dstruct(s, bih, biClrUsed, "lu");
     dstruct(s, bih, biClrImportant, "lu");
 }

 static int shall_we_drop(struct vfw_ctx *ctx)
 {
     AVFormatContext *s = ctx->s;
     const uint8_t dropscore[] = {62, 75, 87, 100};
     const int ndropscores = FF_ARRAY_ELEMS(dropscore);
     unsigned int buffer_fullness = (ctx->curbufsize*100)/s->max_picture_buffer;

     if(dropscore[++ctx->frame_num%ndropscores] <= buffer_fullness) {
         av_log(ctx->s, AV_LOG_ERROR,
               "real-time buffer %d%% full! frame dropped!\n", buffer_fullness);
         return 1;
     }

     return 0;
 }

 static LRESULT CALLBACK videostream_cb(HWND hwnd, LPVIDEOHDR vdhdr)
 {
     struct vfw_ctx *ctx;
     AVPacketList **ppktl, *pktl_next;

     ctx = (struct vfw_ctx *) GetWindowLongPtr(hwnd, GWLP_USERDATA);

     dump_videohdr(ctx->s, vdhdr);

     if(shall_we_drop(ctx))
         return FALSE;

     WaitForSingleObject(ctx->mutex, INFINITE);

     pktl_next = av_mallocz(sizeof(AVPacketList));
     if(!pktl_next)
         goto fail;

     if(av_new_packet(&pktl_next->pkt, vdhdr->dwBytesUsed) < 0) {
         av_free(pktl_next);
         goto fail;
     }

     pktl_next->pkt.pts = vdhdr->dwTimeCaptured;
     memcpy(pktl_next->pkt.data, vdhdr->lpData, vdhdr->dwBytesUsed);

     for(ppktl = &ctx->pktl ; *ppktl ; ppktl = &(*ppktl)->next);
     *ppktl = pktl_next;

     ctx->curbufsize += vdhdr->dwBytesUsed;

     SetEvent(ctx->event);
     ReleaseMutex(ctx->mutex);

     return TRUE;
 fail:
     ReleaseMutex(ctx->mutex);
     return FALSE;
 }

 static int vfw_read_close(AVFormatContext *s);

 static int vfw_read_header(AVFormatContext *s, AVFormatParameters *ap)
 {
     struct vfw_ctx *ctx = s->priv_data;
     AVCodecContext *codec;
     AVStream *st;
     int devnum;
     int bisize;
     BITMAPINFO *bi;
     CAPTUREPARMS cparms;
     DWORD biCompression;
     WORD biBitCount;
     int width;
     int height;
     int ret;

     if(!ap->time_base.den) {
         av_log(s, AV_LOG_ERROR, "A time base must be specified.\n");
         return AVERROR_IO;
     }

     ctx->s = s;

     ctx->hwnd = capCreateCaptureWindow(NULL, 0, 0, 0, 0, 0, HWND_MESSAGE, 0);
     if(!ctx->hwnd) {
         av_log(s, AV_LOG_ERROR, "Could not create capture window.\n");
         return AVERROR_IO;
     }

     /* If atoi fails, devnum==0 and the default device is used */
     devnum = atoi(s->filename);

     ret = SendMessage(ctx->hwnd, WM_CAP_DRIVER_CONNECT, devnum, 0);
     if(!ret) {
         av_log(s, AV_LOG_ERROR, "Could not connect to device.\n");
         DestroyWindow(ctx->hwnd);
         return AVERROR(ENODEV);
     }

     SendMessage(ctx->hwnd, WM_CAP_SET_OVERLAY, 0, 0);
     SendMessage(ctx->hwnd, WM_CAP_SET_PREVIEW, 0, 0);

     ret = SendMessage(ctx->hwnd, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0,
                       (LPARAM) videostream_cb);
     if(!ret) {
         av_log(s, AV_LOG_ERROR, "Could not set video stream callback.\n");
         goto fail_io;
     }

     SetWindowLongPtr(ctx->hwnd, GWLP_USERDATA, (LONG_PTR) ctx);

     st = av_new_stream(s, 0);
     if(!st) {
         vfw_read_close(s);
         return AVERROR_NOMEM;
     }

     /* Set video format */
     bisize = SendMessage(ctx->hwnd, WM_CAP_GET_VIDEOFORMAT, 0, 0);
     if(!bisize)
         goto fail_io;
     bi = av_malloc(bisize);
     if(!bi) {
         vfw_read_close(s);
         return AVERROR_NOMEM;
     }
     ret = SendMessage(ctx->hwnd, WM_CAP_GET_VIDEOFORMAT, bisize, (LPARAM) bi);
     if(!ret)
         goto fail_bi;

     dump_bih(s, &bi->bmiHeader);

     width  = ap->width  ? ap->width  : bi->bmiHeader.biWidth ;
     height = ap->height ? ap->height : bi->bmiHeader.biHeight;
     bi->bmiHeader.biWidth  = width ;
     bi->bmiHeader.biHeight = height;

 #if 0
     /* For testing yet unsupported compressions
      * Copy these values from user-supplied verbose information */
     bi->bmiHeader.biWidth       = 320;
     bi->bmiHeader.biHeight      = 240;
     bi->bmiHeader.biPlanes      = 1;
     bi->bmiHeader.biBitCount    = 12;
     bi->bmiHeader.biCompression = MKTAG('I','4','2','0');
     bi->bmiHeader.biSizeImage   = 115200;
     dump_bih(s, &bi->bmiHeader);
 #endif

     ret = SendMessage(ctx->hwnd, WM_CAP_SET_VIDEOFORMAT, bisize, (LPARAM) bi);
     if(!ret) {
         av_log(s, AV_LOG_ERROR, "Could not set Video Format.\n");
         goto fail_bi;
     }

     biCompression = bi->bmiHeader.biCompression;
     biBitCount = bi->bmiHeader.biBitCount;

     av_free(bi);

     /* Set sequence setup */
     ret = SendMessage(ctx->hwnd, WM_CAP_GET_SEQUENCE_SETUP, sizeof(cparms),
                       (LPARAM) &cparms);
     if(!ret)
         goto fail_io;

     dump_captureparms(s, &cparms);

     cparms.fYield = 1; // Spawn a background thread
     cparms.dwRequestMicroSecPerFrame =
                                (ap->time_base.num*1000000) / ap->time_base.den;
     cparms.fAbortLeftMouse = 0;
     cparms.fAbortRightMouse = 0;
     cparms.fCaptureAudio = 0;
     cparms.vKeyAbort = 0;

     ret = SendMessage(ctx->hwnd, WM_CAP_SET_SEQUENCE_SETUP, sizeof(cparms),
                       (LPARAM) &cparms);
     if(!ret)
         goto fail_io;

     codec = st->codec;
     codec->time_base = ap->time_base;
     codec->codec_type = CODEC_TYPE_VIDEO;
     codec->width = width;
     codec->height = height;
     codec->codec_id = CODEC_ID_RAWVIDEO;
     codec->pix_fmt = vfw_pixfmt(biCompression, biBitCount);
     if(biCompression == BI_RGB)
         codec->bits_per_coded_sample = biBitCount;

     av_set_pts_info(st, 32, 1, 1000);

     if(codec->pix_fmt == -1) {
         av_log(s, AV_LOG_ERROR, "Unknown compression type."
                          "Please report verbose (-v 99) debug information.\n");
         vfw_read_close(s);
         return AVERROR_PATCHWELCOME;
     }

     ctx->mutex = CreateMutex(NULL, 0, NULL);
     if(!ctx->mutex) {
         av_log(s, AV_LOG_ERROR, "Could not create Mutex.\n" );
         goto fail_io;
     }
     ctx->event = CreateEvent(NULL, 1, 0, NULL);
     if(!ctx->event) {
         av_log(s, AV_LOG_ERROR, "Could not create Event.\n" );
         goto fail_io;
     }

     ret = SendMessage(ctx->hwnd, WM_CAP_SEQUENCE_NOFILE, 0, 0);
     if(!ret) {
         av_log(s, AV_LOG_ERROR, "Could not start capture sequence.\n" );
         goto fail_io;
     }

     return 0;

 fail_bi:
     av_free(bi);

 fail_io:
     vfw_read_close(s);
     return AVERROR_IO;
 }

 static int vfw_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     struct vfw_ctx *ctx = s->priv_data;
     AVPacketList *pktl = NULL;

     while(!pktl) {
         WaitForSingleObject(ctx->mutex, INFINITE);
         pktl = ctx->pktl;
         if(ctx->pktl) {
             *pkt = ctx->pktl->pkt;
             ctx->pktl = ctx->pktl->next;
             av_free(pktl);
         }
         ResetEvent(ctx->event);
         ReleaseMutex(ctx->mutex);
         if(!pktl) {
             if(s->flags & AVFMT_FLAG_NONBLOCK) {
                 return AVERROR(EAGAIN);
             } else {
                 WaitForSingleObject(ctx->event, INFINITE);
             }
         }
     }

     ctx->curbufsize -= pkt->size;

     return pkt->size;
 }

 static int vfw_read_close(AVFormatContext *s)
 {
     struct vfw_ctx *ctx = s->priv_data;

     if(ctx->hwnd) {
         SendMessage(ctx->hwnd, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0, 0);
         SendMessage(ctx->hwnd, WM_CAP_DRIVER_DISCONNECT, 0, 0);
         DestroyWindow(ctx->hwnd);
     }
     if(ctx->mutex)
         CloseHandle(ctx->mutex);
     if(ctx->event)
         CloseHandle(ctx->event);

     return 0;
 }

 AVInputFormat vfwcap_demuxer = {
     "vfwcap",
     NULL_IF_CONFIG_SMALL("VFW video capture"),
     sizeof(struct vfw_ctx),
     NULL,
     vfw_read_header,
     vfw_read_packet,
     vfw_read_close,
     .flags = AVFMT_NOFILE,
 };
	/*
	* VFW capture interface
	* Copyright (c) 2006-2008 Ramiro Polla
	*
	* 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 "libavformat/avformat.h"
	#include <windows.h>
	#include <vfw.h>

	//#define DEBUG_VFW

	/* Defines for VFW missing from MinGW.
	* Remove this when MinGW incorporates them. */
	#define HWND_MESSAGE ((HWND)-3)

	#define BI_RGB 0

	/* End of missing MinGW defines */

	struct vfw_ctx {
	HWND hwnd;
	HANDLE mutex;
	HANDLE event;
	AVPacketList *pktl;
	AVFormatContext *s;
	unsigned int curbufsize;
	unsigned int frame_num;
	};

	static enum PixelFormat vfw_pixfmt(DWORD biCompression, WORD biBitCount)
	{
	switch(biCompression) {
	case MKTAG('Y', 'U', 'Y', '2'):
	return PIX_FMT_YUYV422;
	case MKTAG('I', '4', '2', '0'):
	return PIX_FMT_YUV420P;
	case BI_RGB:
	switch(biBitCount) { /* 1-8 are untested */
	case 1:
	return PIX_FMT_MONOWHITE;
	case 4:
	return PIX_FMT_RGB4;
	case 8:
	return PIX_FMT_RGB8;
	case 16:
	return PIX_FMT_RGB555;
	case 24:
	return PIX_FMT_BGR24;
	case 32:
	return PIX_FMT_RGB32;
	}
	}
	return -1;
	}

	#define dstruct(pctx, sname, var, type) \
	av_log(pctx, AV_LOG_DEBUG, #var":\t%"type"\n", sname->var)

	static void dump_captureparms(AVFormatContext s, CAPTUREPARMS cparms)
	{
	av_log(s, AV_LOG_DEBUG, "CAPTUREPARMS\n");
	dstruct(s, cparms, dwRequestMicroSecPerFrame, "lu");
	dstruct(s, cparms, fMakeUserHitOKToCapture, "d");
	dstruct(s, cparms, wPercentDropForError, "u");
	dstruct(s, cparms, fYield, "d");
	dstruct(s, cparms, dwIndexSize, "lu");
	dstruct(s, cparms, wChunkGranularity, "u");
	dstruct(s, cparms, fUsingDOSMemory, "d");
	dstruct(s, cparms, wNumVideoRequested, "u");
	dstruct(s, cparms, fCaptureAudio, "d");
	dstruct(s, cparms, wNumAudioRequested, "u");
	dstruct(s, cparms, vKeyAbort, "u");
	dstruct(s, cparms, fAbortLeftMouse, "d");
	dstruct(s, cparms, fAbortRightMouse, "d");
	dstruct(s, cparms, fLimitEnabled, "d");
	dstruct(s, cparms, wTimeLimit, "u");
	dstruct(s, cparms, fMCIControl, "d");
	dstruct(s, cparms, fStepMCIDevice, "d");
	dstruct(s, cparms, dwMCIStartTime, "lu");
	dstruct(s, cparms, dwMCIStopTime, "lu");
	dstruct(s, cparms, fStepCaptureAt2x, "d");
	dstruct(s, cparms, wStepCaptureAverageFrames, "u");
	dstruct(s, cparms, dwAudioBufferSize, "lu");
	dstruct(s, cparms, fDisableWriteCache, "d");
	dstruct(s, cparms, AVStreamMaster, "u");
	}

	static void dump_videohdr(AVFormatContext s, VIDEOHDR vhdr)
	{
	#ifdef DEBUG_VFW
	av_log(s, AV_LOG_DEBUG, "VIDEOHDR\n");
	dstruct(s, vhdr, lpData, "p");
	dstruct(s, vhdr, dwBufferLength, "lu");
	dstruct(s, vhdr, dwBytesUsed, "lu");
	dstruct(s, vhdr, dwTimeCaptured, "lu");
	dstruct(s, vhdr, dwUser, "lu");
	dstruct(s, vhdr, dwFlags, "lu");
	dstruct(s, vhdr, dwReserved[0], "lu");
	dstruct(s, vhdr, dwReserved[1], "lu");
	dstruct(s, vhdr, dwReserved[2], "lu");
	dstruct(s, vhdr, dwReserved[3], "lu");
	#endif
	}

	static void dump_bih(AVFormatContext s, BITMAPINFOHEADER bih)
	{
	av_log(s, AV_LOG_DEBUG, "BITMAPINFOHEADER\n");
	dstruct(s, bih, biSize, "lu");
	dstruct(s, bih, biWidth, "ld");
	dstruct(s, bih, biHeight, "ld");
	dstruct(s, bih, biPlanes, "d");
	dstruct(s, bih, biBitCount, "d");
	dstruct(s, bih, biCompression, "lu");
	av_log(s, AV_LOG_DEBUG, " biCompression:\t\"%.4s\"\n",
	(char*) &bih->biCompression);
	dstruct(s, bih, biSizeImage, "lu");
	dstruct(s, bih, biXPelsPerMeter, "lu");
	dstruct(s, bih, biYPelsPerMeter, "lu");
	dstruct(s, bih, biClrUsed, "lu");
	dstruct(s, bih, biClrImportant, "lu");
	}

	static int shall_we_drop(struct vfw_ctx *ctx)
	{
	AVFormatContext *s = ctx->s;
	const uint8_t dropscore[] = {62, 75, 87, 100};
	const int ndropscores = FF_ARRAY_ELEMS(dropscore);
	unsigned int buffer_fullness = (ctx->curbufsize*100)/s->max_picture_buffer;

	if(dropscore[++ctx->frame_num%ndropscores] <= buffer_fullness) {
	av_log(ctx->s, AV_LOG_ERROR,
	"real-time buffer %d%% full! frame dropped!\n", buffer_fullness);
	return 1;
	}

	return 0;
	}

	static LRESULT CALLBACK videostream_cb(HWND hwnd, LPVIDEOHDR vdhdr)
	{
	struct vfw_ctx *ctx;
	AVPacketList *ppktl, pktl_next;

	ctx = (struct vfw_ctx *) GetWindowLongPtr(hwnd, GWLP_USERDATA);

	dump_videohdr(ctx->s, vdhdr);

	if(shall_we_drop(ctx))
	return FALSE;

	WaitForSingleObject(ctx->mutex, INFINITE);

	pktl_next = av_mallocz(sizeof(AVPacketList));
	if(!pktl_next)
	goto fail;

	if(av_new_packet(&pktl_next->pkt, vdhdr->dwBytesUsed) < 0) {
	av_free(pktl_next);
	goto fail;
	}

	pktl_next->pkt.pts = vdhdr->dwTimeCaptured;
	memcpy(pktl_next->pkt.data, vdhdr->lpData, vdhdr->dwBytesUsed);

	for(ppktl = &ctx->pktl ; ppktl ; ppktl = &(ppktl)->next);
	*ppktl = pktl_next;

	ctx->curbufsize += vdhdr->dwBytesUsed;

	SetEvent(ctx->event);
	ReleaseMutex(ctx->mutex);

	return TRUE;
	fail:
	ReleaseMutex(ctx->mutex);
	return FALSE;
	}

	static int vfw_read_close(AVFormatContext *s);

	static int vfw_read_header(AVFormatContext s, AVFormatParameters ap)
	{
	struct vfw_ctx *ctx = s->priv_data;
	AVCodecContext *codec;
	AVStream *st;
	int devnum;
	int bisize;
	BITMAPINFO *bi;
	CAPTUREPARMS cparms;
	DWORD biCompression;
	WORD biBitCount;
	int width;
	int height;
	int ret;

	if(!ap->time_base.den) {
	av_log(s, AV_LOG_ERROR, "A time base must be specified.\n");
	return AVERROR_IO;
	}

	ctx->s = s;

	ctx->hwnd = capCreateCaptureWindow(NULL, 0, 0, 0, 0, 0, HWND_MESSAGE, 0);
	if(!ctx->hwnd) {
	av_log(s, AV_LOG_ERROR, "Could not create capture window.\n");
	return AVERROR_IO;
	}

	/* If atoi fails, devnum==0 and the default device is used */
	devnum = atoi(s->filename);

	ret = SendMessage(ctx->hwnd, WM_CAP_DRIVER_CONNECT, devnum, 0);
	if(!ret) {
	av_log(s, AV_LOG_ERROR, "Could not connect to device.\n");
	DestroyWindow(ctx->hwnd);
	return AVERROR(ENODEV);
	}

	SendMessage(ctx->hwnd, WM_CAP_SET_OVERLAY, 0, 0);
	SendMessage(ctx->hwnd, WM_CAP_SET_PREVIEW, 0, 0);

	ret = SendMessage(ctx->hwnd, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0,
	(LPARAM) videostream_cb);
	if(!ret) {
	av_log(s, AV_LOG_ERROR, "Could not set video stream callback.\n");
	goto fail_io;
	}

	SetWindowLongPtr(ctx->hwnd, GWLP_USERDATA, (LONG_PTR) ctx);

	st = av_new_stream(s, 0);
	if(!st) {
	vfw_read_close(s);
	return AVERROR_NOMEM;
	}

	/* Set video format */
	bisize = SendMessage(ctx->hwnd, WM_CAP_GET_VIDEOFORMAT, 0, 0);
	if(!bisize)
	goto fail_io;
	bi = av_malloc(bisize);
	if(!bi) {
	vfw_read_close(s);
	return AVERROR_NOMEM;
	}
	ret = SendMessage(ctx->hwnd, WM_CAP_GET_VIDEOFORMAT, bisize, (LPARAM) bi);
	if(!ret)
	goto fail_bi;

	dump_bih(s, &bi->bmiHeader);

	width = ap->width ? ap->width : bi->bmiHeader.biWidth ;
	height = ap->height ? ap->height : bi->bmiHeader.biHeight;
	bi->bmiHeader.biWidth = width ;
	bi->bmiHeader.biHeight = height;

	#if 0
	/* For testing yet unsupported compressions
	* Copy these values from user-supplied verbose information */
	bi->bmiHeader.biWidth = 320;
	bi->bmiHeader.biHeight = 240;
	bi->bmiHeader.biPlanes = 1;
	bi->bmiHeader.biBitCount = 12;
	bi->bmiHeader.biCompression = MKTAG('I','4','2','0');
	bi->bmiHeader.biSizeImage = 115200;
	dump_bih(s, &bi->bmiHeader);
	#endif

	ret = SendMessage(ctx->hwnd, WM_CAP_SET_VIDEOFORMAT, bisize, (LPARAM) bi);
	if(!ret) {
	av_log(s, AV_LOG_ERROR, "Could not set Video Format.\n");
	goto fail_bi;
	}

	biCompression = bi->bmiHeader.biCompression;
	biBitCount = bi->bmiHeader.biBitCount;

	av_free(bi);

	/* Set sequence setup */
	ret = SendMessage(ctx->hwnd, WM_CAP_GET_SEQUENCE_SETUP, sizeof(cparms),
	(LPARAM) &cparms);
	if(!ret)
	goto fail_io;

	dump_captureparms(s, &cparms);

	cparms.fYield = 1; // Spawn a background thread
	cparms.dwRequestMicroSecPerFrame =
	(ap->time_base.num*1000000) / ap->time_base.den;
	cparms.fAbortLeftMouse = 0;
	cparms.fAbortRightMouse = 0;
	cparms.fCaptureAudio = 0;
	cparms.vKeyAbort = 0;

	ret = SendMessage(ctx->hwnd, WM_CAP_SET_SEQUENCE_SETUP, sizeof(cparms),
	(LPARAM) &cparms);
	if(!ret)
	goto fail_io;

	codec = st->codec;
	codec->time_base = ap->time_base;
	codec->codec_type = CODEC_TYPE_VIDEO;
	codec->width = width;
	codec->height = height;
	codec->codec_id = CODEC_ID_RAWVIDEO;
	codec->pix_fmt = vfw_pixfmt(biCompression, biBitCount);
	if(biCompression == BI_RGB)
	codec->bits_per_coded_sample = biBitCount;

	av_set_pts_info(st, 32, 1, 1000);

	if(codec->pix_fmt == -1) {
	av_log(s, AV_LOG_ERROR, "Unknown compression type."
	"Please report verbose (-v 99) debug information.\n");
	vfw_read_close(s);
	return AVERROR_PATCHWELCOME;
	}

	ctx->mutex = CreateMutex(NULL, 0, NULL);
	if(!ctx->mutex) {
	av_log(s, AV_LOG_ERROR, "Could not create Mutex.\n" );
	goto fail_io;
	}
	ctx->event = CreateEvent(NULL, 1, 0, NULL);
	if(!ctx->event) {
	av_log(s, AV_LOG_ERROR, "Could not create Event.\n" );
	goto fail_io;
	}

	ret = SendMessage(ctx->hwnd, WM_CAP_SEQUENCE_NOFILE, 0, 0);
	if(!ret) {
	av_log(s, AV_LOG_ERROR, "Could not start capture sequence.\n" );
	goto fail_io;
	}

	return 0;

	fail_bi:
	av_free(bi);

	fail_io:
	vfw_read_close(s);
	return AVERROR_IO;
	}

	static int vfw_read_packet(AVFormatContext s, AVPacket pkt)
	{
	struct vfw_ctx *ctx = s->priv_data;
	AVPacketList *pktl = NULL;

	while(!pktl) {
	WaitForSingleObject(ctx->mutex, INFINITE);
	pktl = ctx->pktl;
	if(ctx->pktl) {
	*pkt = ctx->pktl->pkt;
	ctx->pktl = ctx->pktl->next;
	av_free(pktl);
	}
	ResetEvent(ctx->event);
	ReleaseMutex(ctx->mutex);
	if(!pktl) {
	if(s->flags & AVFMT_FLAG_NONBLOCK) {
	return AVERROR(EAGAIN);
	} else {
	WaitForSingleObject(ctx->event, INFINITE);
	}
	}
	}

	ctx->curbufsize -= pkt->size;

	return pkt->size;
	}

	static int vfw_read_close(AVFormatContext *s)
	{
	struct vfw_ctx *ctx = s->priv_data;

	if(ctx->hwnd) {
	SendMessage(ctx->hwnd, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0, 0);
	SendMessage(ctx->hwnd, WM_CAP_DRIVER_DISCONNECT, 0, 0);
	DestroyWindow(ctx->hwnd);
	}
	if(ctx->mutex)
	CloseHandle(ctx->mutex);
	if(ctx->event)
	CloseHandle(ctx->event);

	return 0;
	}

	AVInputFormat vfwcap_demuxer = {
	"vfwcap",
	NULL_IF_CONFIG_SMALL("VFW video capture"),
	sizeof(struct vfw_ctx),
	NULL,
	vfw_read_header,
	vfw_read_packet,
	vfw_read_close,
	.flags = AVFMT_NOFILE,
	};