st/va: detect MJPEG format from bitstream

To find if the format is supported YUYV by sampling factor which
is embedded from bitstream. So we could use this info for buffer
reallocation on the correct format.

Signed-off-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

src/gallium/state_trackers/va/picture.c

@@ -65,6 +65,7 @@ vlVaBeginPicture(VADriverContextP ctx, VAContextID context_id, VASurfaceID rende
    context->target_id = render_target;
    surf->ctx = context_id;
    context->target = surf->buffer;
+   context->mjpeg.sampling_factor = 0;
 
    if (!context->decoder) {
 

src/gallium/state_trackers/va/picture_mjpeg.c

@@ -30,6 +30,7 @@
 void vlVaHandlePictureParameterBufferMJPEG(vlVaDriver *drv, vlVaContext *context, vlVaBuffer *buf)
 {
    VAPictureParameterBufferJPEGBaseline *mjpeg = buf->data;
+   unsigned sf;
    int i;
 
    assert(buf->size >= sizeof(VAPictureParameterBufferJPEGBaseline) && buf->num_elements == 1);
@@ -46,6 +47,10 @@ void vlVaHandlePictureParameterBufferMJPEG(vlVaDriver *drv, vlVaContext *context
          mjpeg->components[i].v_sampling_factor;
       context->desc.mjpeg.picture_parameter.components[i].quantiser_table_selector =
          mjpeg->components[i].quantiser_table_selector;
+
+      sf = mjpeg->components[i].h_sampling_factor << 4 | mjpeg->components[i].v_sampling_factor;
+      context->mjpeg.sampling_factor <<= 8;
+      context->mjpeg.sampling_factor |= sf;
    }
 
    context->desc.mjpeg.picture_parameter.num_components = mjpeg->num_components;

src/gallium/state_trackers/va/va_private.h

@@ -277,6 +277,10 @@ typedef struct {
       uint8_t start_code[32];
    } mpeg4;
 
+   struct {
+      unsigned sampling_factor;
+   } mjpeg;
+
    struct vl_deint_filter *deint;
    vlVaBuffer *coded_buf;
    int target_id;