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mirror of https://github.com/FFmpeg/FFmpeg.git synced 2024-12-23 12:43:46 +02:00

dshow: handle events in graph

Handling DirectShow events prevents infinite loops when there is an error in
the graph, such as a device being disconnected. This makes it possible for
dshow to return an error to the caller and run the cleanup code.

Based on patch by Don Moir <donmoir@comcast.net>.
This commit is contained in:
Ramiro Polla 2012-12-17 03:44:12 -02:00
parent 2e59142fa9
commit 190f6135b4
2 changed files with 70 additions and 11 deletions

View File

@ -45,13 +45,17 @@ struct dshow_ctx {
libAVPin *capture_pin[2];
HANDLE mutex;
HANDLE event;
HANDLE event[2]; /* event[0] is set by DirectShow
* event[1] is set by callback() */
AVPacketList *pktl;
int eof;
int64_t curbufsize;
unsigned int video_frame_num;
IMediaControl *control;
IMediaEvent *media_event;
enum AVPixelFormat pixel_format;
enum AVCodecID video_codec_id;
@ -118,6 +122,9 @@ dshow_read_close(AVFormatContext *s)
IMediaControl_Release(ctx->control);
}
if (ctx->media_event)
IMediaEvent_Release(ctx->media_event);
if (ctx->graph) {
IEnumFilters *fenum;
int r;
@ -161,8 +168,10 @@ dshow_read_close(AVFormatContext *s)
if(ctx->mutex)
CloseHandle(ctx->mutex);
if(ctx->event)
CloseHandle(ctx->event);
if(ctx->event[0])
CloseHandle(ctx->event[0]);
if(ctx->event[1])
CloseHandle(ctx->event[1]);
pktl = ctx->pktl;
while (pktl) {
@ -233,7 +242,7 @@ callback(void *priv_data, int index, uint8_t *buf, int buf_size, int64_t time)
ctx->curbufsize += buf_size;
SetEvent(ctx->event);
SetEvent(ctx->event[1]);
ReleaseMutex(ctx->mutex);
return;
@ -868,6 +877,9 @@ static int dshow_read_header(AVFormatContext *avctx)
IGraphBuilder *graph = NULL;
ICreateDevEnum *devenum = NULL;
IMediaControl *control = NULL;
IMediaEvent *media_event = NULL;
HANDLE media_event_handle;
HANDLE proc;
int ret = AVERROR(EIO);
int r;
@ -948,8 +960,8 @@ static int dshow_read_header(AVFormatContext *avctx)
av_log(avctx, AV_LOG_ERROR, "Could not create Mutex\n");
goto error;
}
ctx->event = CreateEvent(NULL, 1, 0, NULL);
if (!ctx->event) {
ctx->event[1] = CreateEvent(NULL, 1, 0, NULL);
if (!ctx->event[1]) {
av_log(avctx, AV_LOG_ERROR, "Could not create Event\n");
goto error;
}
@ -961,6 +973,26 @@ static int dshow_read_header(AVFormatContext *avctx)
}
ctx->control = control;
r = IGraphBuilder_QueryInterface(graph, &IID_IMediaEvent, (void **) &media_event);
if (r != S_OK) {
av_log(avctx, AV_LOG_ERROR, "Could not get media event.\n");
goto error;
}
ctx->media_event = media_event;
r = IMediaEvent_GetEventHandle(media_event, (void *) &media_event_handle);
if (r != S_OK) {
av_log(avctx, AV_LOG_ERROR, "Could not get media event handle.\n");
goto error;
}
proc = GetCurrentProcess();
r = DuplicateHandle(proc, media_event_handle, proc, &ctx->event[0],
0, 0, DUPLICATE_SAME_ACCESS);
if (!r) {
av_log(avctx, AV_LOG_ERROR, "Could not duplicate media event handle.\n");
goto error;
}
r = IMediaControl_Run(control);
if (r == S_FALSE) {
OAFilterState pfs;
@ -984,12 +1016,32 @@ error:
return ret;
}
/**
* Checks media events from DirectShow and returns -1 on error or EOF. Also
* purges all events that might be in the event queue to stop the trigger
* of event notification.
*/
static int dshow_check_event_queue(IMediaEvent *media_event)
{
LONG_PTR p1, p2;
long code;
int ret = 0;
while (IMediaEvent_GetEvent(media_event, &code, &p1, &p2, 0) != E_ABORT) {
if (code == EC_COMPLETE || code == EC_DEVICE_LOST || code == EC_ERRORABORT)
ret = -1;
IMediaEvent_FreeEventParams(media_event, code, p1, p2);
}
return ret;
}
static int dshow_read_packet(AVFormatContext *s, AVPacket *pkt)
{
struct dshow_ctx *ctx = s->priv_data;
AVPacketList *pktl = NULL;
while (!pktl) {
while (!ctx->eof && !pktl) {
WaitForSingleObject(ctx->mutex, INFINITE);
pktl = ctx->pktl;
if (pktl) {
@ -998,18 +1050,20 @@ static int dshow_read_packet(AVFormatContext *s, AVPacket *pkt)
av_free(pktl);
ctx->curbufsize -= pkt->size;
}
ResetEvent(ctx->event);
ResetEvent(ctx->event[1]);
ReleaseMutex(ctx->mutex);
if (!pktl) {
if (s->flags & AVFMT_FLAG_NONBLOCK) {
if (dshow_check_event_queue(ctx->media_event) < 0) {
ctx->eof = 1;
} else if (s->flags & AVFMT_FLAG_NONBLOCK) {
return AVERROR(EAGAIN);
} else {
WaitForSingleObject(ctx->event, INFINITE);
WaitForMultipleObjects(2, ctx->event, 0, INFINITE);
}
}
}
return pkt->size;
return ctx->eof ? AVERROR(EIO) : pkt->size;
}
#define OFFSET(x) offsetof(struct dshow_ctx, x)

View File

@ -32,6 +32,11 @@
#include <dshow.h>
#include <dvdmedia.h>
/* EC_DEVICE_LOST is not defined in MinGW dshow headers. */
#ifndef EC_DEVICE_LOST
#define EC_DEVICE_LOST 0x1f
#endif
long ff_copy_dshow_media_type(AM_MEDIA_TYPE *dst, const AM_MEDIA_TYPE *src);
void ff_print_VIDEO_STREAM_CONFIG_CAPS(const VIDEO_STREAM_CONFIG_CAPS *caps);
void ff_print_AUDIO_STREAM_CONFIG_CAPS(const AUDIO_STREAM_CONFIG_CAPS *caps);