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videodecoder: parse any source data that is still available.

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Fix gst_video_decoder_parse_available() to really parse any pending
source data that is still available in the adapter. This is a memory
optimization to avoid expansion of video packed added to the adapter,
but also a fix to EOS condition when the subclass parse() function
ultimately only needed to call into gvd_have_frame() and no additional
source bytes were consumed, i.e. gvd_add_to_frame() is not called.

This situation can occur when decoding H.264 streams in byte-stream/nal
mode for instance. A decoder always requires the next NAL unit to be
parsed so that to determine picture boundaries. When a new picture is
found, no byte is consumed (i.e. gvd_add_to_frame() is not called)
but gvd_have_frame() is called (i.e. priv->current_frame is gone).

Also make sure to avoid infinite loops caused by incorrect subclass
parse() implementations. This can occur when no byte gets consumed
and no appropriate indication (GST_VIDEO_DECODER_FLOW_NEED_DATA) is
returned.

https://bugzilla.gnome.org/show_bug.cgi?id=731974

Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
This commit is contained in:
Gwenole Beauchesne 2014-06-20 18:02:31 +02:00
parent 9a25e59e12
commit fb44ec9615
1 changed files with 25 additions and 5 deletions
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30
gst-libs/gst/video/gstvideodecoder.c
View file

@ -926,26 +926,46 @@ gst_video_decoder_parse_available (GstVideoDecoder * dec, gboolean at_eos,
GstVideoDecoderClass *decoder_class = GST_VIDEO_DECODER_GET_CLASS (dec);
GstVideoDecoderPrivate *priv = dec->priv;
GstFlowReturn ret = GST_FLOW_OK;
gsize start_size, available;
gsize was_available, available;
guint inactive = 0;
available = gst_adapter_available (priv->input_adapter);
start_size = 0;
while (ret == GST_FLOW_OK && ((available && start_size != available)
|| new_buffer)) {
while (available || new_buffer) {
new_buffer = FALSE;
/* current frame may have been parsed and handled,
* so we need to set up a new one when asking subclass to parse */
if (priv->current_frame == NULL)
priv->current_frame = gst_video_decoder_new_frame (dec);
start_size = available;
was_available = available;
ret = decoder_class->parse (dec, priv->current_frame,
priv->input_adapter, at_eos);
if (ret != GST_FLOW_OK)
break;
/* if the subclass returned success (GST_FLOW_OK), it is expected
* to have collected and submitted a frame, i.e. it should have
* called gst_video_decoder_have_frame(), or at least consumed a
* few bytes through gst_video_decoder_add_to_frame().
*
* Otherwise, this is an implementation bug, and we error out
* after 2 failed attempts */
available = gst_adapter_available (priv->input_adapter);
if (!priv->current_frame || available != was_available)
inactive = 0;
else if (++inactive == 2)
goto error_inactive;
}
return ret;
/* ERRORS */
error_inactive:
{
GST_ERROR_OBJECT (dec, "Failed to consume data. Error in subclass?");
return GST_FLOW_ERROR;
}
}
static GstFlowReturn