[FFmpeg-trac] #1976(avdevice:new): dshow_read_header can return zero when it fails

[FFmpeg]

#1976: dshow_read_header can return zero when it fails
----------------------------------+---------------------------------------
             Reporter:  DonMoir   |                     Type:  defect
               Status:  new       |                 Priority:  critical
            Component:  avdevice  |                  Version:  unspecified
             Keywords:            |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
----------------------------------+---------------------------------------
 When a camera is already open say in another app, dshow_open_device will
 succeed in dshow_read_header and the ret value for dshow_read_header will
 now indicate success. If dshow_read_header fails after the open device
 calls, a ret value of zero is set indicating a successful open.

 When the camera is already running in another app, all will succeed except
 IMediaControl_Run will fail and it will goto error with a success ret
 value.

 After the dshow_open_device && dshow_add_device calls I just added ret =
 AVERROR(EIO); although it should be structured better.


 {{{
 static int dshow_read_header(AVFormatContext *avctx)
 {
     struct dshow_ctx *ctx = avctx->priv_data;
     IGraphBuilder *graph = NULL;
     ICreateDevEnum *devenum = NULL;
     IMediaControl *control = NULL;
     int ret = AVERROR(EIO);
     int r;

     if (!ctx->list_devices && !parse_device_name(avctx)) {
         av_log(avctx, AV_LOG_ERROR, "Malformed dshow input string.\n");
         goto error;
     }

     ctx->video_codec_id = avctx->video_codec_id ? avctx->video_codec_id
                                                 : AV_CODEC_ID_RAWVIDEO;
     if (ctx->pixel_format != AV_PIX_FMT_NONE) {
         if (ctx->video_codec_id != AV_CODEC_ID_RAWVIDEO) {
             av_log(avctx, AV_LOG_ERROR, "Pixel format may only be set when
 "
                               "video codec is not set or set to
 rawvideo\n");
             ret = AVERROR(EINVAL);
             goto error;
         }
     }
     if (ctx->framerate) {
         r = av_parse_video_rate(&ctx->requested_framerate,
 ctx->framerate);
         if (r < 0) {
             av_log(avctx, AV_LOG_ERROR, "Could not parse framerate
 '%s'.\n", ctx->framerate);
             goto error;
         }
     }

     CoInitialize(0);

     r = CoCreateInstance(&CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER,
                          &IID_IGraphBuilder, (void **) &graph);
     if (r != S_OK) {
         av_log(avctx, AV_LOG_ERROR, "Could not create capture graph.\n");
         goto error;
     }
     ctx->graph = graph;

     r = CoCreateInstance(&CLSID_SystemDeviceEnum, NULL,
 CLSCTX_INPROC_SERVER,
                          &IID_ICreateDevEnum, (void **) &devenum);
     if (r != S_OK) {
         av_log(avctx, AV_LOG_ERROR, "Could not enumerate system
 devices.\n");
         goto error;
     }

     if (ctx->list_devices) {
         av_log(avctx, AV_LOG_INFO, "DirectShow video devices\n");
         dshow_cycle_devices(avctx, devenum, VideoDevice, NULL);
         av_log(avctx, AV_LOG_INFO, "DirectShow audio devices\n");
         dshow_cycle_devices(avctx, devenum, AudioDevice, NULL);
         ret = AVERROR_EXIT;
         goto error;
     }
     if (ctx->list_options) {
         if (ctx->device_name[VideoDevice])
             dshow_list_device_options(avctx, devenum, VideoDevice);
         if (ctx->device_name[AudioDevice])
             dshow_list_device_options(avctx, devenum, AudioDevice);
         ret = AVERROR_EXIT;
         goto error;
     }

     if (ctx->device_name[VideoDevice]) {
         ret = dshow_open_device(avctx, devenum, VideoDevice);
         if (ret < 0)
             goto error;
         ret = dshow_add_device(avctx, VideoDevice);
         if (ret < 0)
             goto error;
     }
     if (ctx->device_name[AudioDevice]) {
         ret = dshow_open_device(avctx, devenum, AudioDevice);
         if (ret < 0)
             goto error;
         ret = dshow_add_device(avctx, AudioDevice);
         if (ret < 0)
             goto error;
     }

 +   ret = AVERROR(EIO);

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

     r = IGraphBuilder_QueryInterface(graph, &IID_IMediaControl, (void **)
 &control);
     if (r != S_OK) {
         av_log(avctx, AV_LOG_ERROR, "Could not get media control.\n");
         goto error;
     }
     ctx->control = control;

     r = IMediaControl_Run(control);
     if (r == S_FALSE) {
         OAFilterState pfs;
         r = IMediaControl_GetState(control, 0, &pfs);
     }
     if (r != S_OK) {
         av_log(avctx, AV_LOG_ERROR, "Could not run filter\n");
         goto error;
     }

     ret = 0;

 error:

     if (ret < 0)
         dshow_read_close(avctx);

     if (devenum)
         ICreateDevEnum_Release(devenum);

     return ret;
 }
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1976>
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