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decoder: h264: add support for NALU "alignment" optimization.

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We can avoid scanning for start codes again if the bitstream is fed
in NALU chunks. Currently, we always scan for start codes, and keep
track of remaining bits in a GstAdapter, even if, in practice, we
are likely receiving one GstBuffer per NAL unit. i.e. h264parse with
"nal" alignment.

https://bugzilla.gnome.org/show_bug.cgi?id=723284

[use gst_adapter_available_fast() to determine the top buffer size]
Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
This commit is contained in:
Sreerenj Balachandran 2014-02-06 08:30:10 +02:00 committed by Gwenole Beauchesne
parent 95c781c34f
commit cb9f98f0d5
3 changed files with 93 additions and 22 deletions
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74
gst-libs/gst/vaapi/gstvaapidecoder_h264.c
View file

@ -445,6 +445,7 @@ struct _GstVaapiDecoderH264Private {
GstH264NalParser *parser;
guint parser_state;
guint decoder_state;
GstVaapiStreamAlignH264 stream_alignment;
GstVaapiPictureH264 *current_picture;
GstVaapiParserInfoH264 *sps[GST_H264_MAX_SPS_COUNT];
GstVaapiParserInfoH264 *active_sps;
@ -3880,7 +3881,14 @@ gst_vaapi_decoder_h264_parse(GstVaapiDecoder *base_decoder,
if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
return status;
size = gst_adapter_available(adapter);
switch (priv->stream_alignment) {
case GST_VAAPI_STREAM_ALIGN_H264_NALU:
size = gst_adapter_available_fast(adapter);
break;
default:
size = gst_adapter_available(adapter);
break;
}
if (priv->is_avcC) {
if (size < priv->nal_length_size)
@ -3902,30 +3910,34 @@ gst_vaapi_decoder_h264_parse(GstVaapiDecoder *base_decoder,
if (size < 4)
return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;
ofs = scan_for_start_code(adapter, 0, size, NULL);
if (ofs < 0)
return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;
if (ofs > 0) {
gst_adapter_flush(adapter, ofs);
size -= ofs;
}
ofs2 = ps->input_offset2 - ofs - 4;
if (ofs2 < 4)
ofs2 = 4;
ofs = G_UNLIKELY(size < ofs2 + 4) ? -1 :
scan_for_start_code(adapter, ofs2, size - ofs2, NULL);
if (ofs < 0) {
// Assume the whole NAL unit is present if end-of-stream
if (!at_eos) {
ps->input_offset2 = size;
if (priv->stream_alignment == GST_VAAPI_STREAM_ALIGN_H264_NALU)
buf_size = size;
else {
ofs = scan_for_start_code(adapter, 0, size, NULL);
if (ofs < 0)
return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;
if (ofs > 0) {
gst_adapter_flush(adapter, ofs);
size -= ofs;
}
ofs = size;
ofs2 = ps->input_offset2 - ofs - 4;
if (ofs2 < 4)
ofs2 = 4;
ofs = G_UNLIKELY(size < ofs2 + 4) ? -1 :
scan_for_start_code(adapter, ofs2, size - ofs2, NULL);
if (ofs < 0) {
// Assume the whole NAL unit is present if end-of-stream
if (!at_eos) {
ps->input_offset2 = size;
return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;
}
ofs = size;
}
buf_size = ofs;
}
buf_size = ofs;
}
ps->input_offset2 = 0;
@ -4127,6 +4139,24 @@ gst_vaapi_decoder_h264_class(void)
return GST_VAAPI_DECODER_CLASS(&g_class);
}
/**
* gst_vaapi_decoder_h264_set_alignment:
* @decoder: a #GstVaapiDecoderH264
* @alignment: the #GstVaapiStreamAlignH264
*
* Specifies how stream buffers are aligned / fed, i.e. the boundaries
* of each buffer that is supplied to the decoder. This could be no
* specific alignment, NAL unit boundaries, or access unit boundaries.
*/
void
gst_vaapi_decoder_h264_set_alignment(GstVaapiDecoderH264 *decoder,
GstVaapiStreamAlignH264 alignment)
{
g_return_if_fail(decoder != NULL);
decoder->priv.stream_alignment = alignment;
}
/**
* gst_vaapi_decoder_h264_new:
* @display: a #GstVaapiDisplay

23
gst-libs/gst/vaapi/gstvaapidecoder_h264.h
View file

@ -27,11 +27,34 @@
G_BEGIN_DECLS
#define GST_VAAPI_DECODER_H264(decoder) \
((GstVaapiDecoderH264 *)(decoder))
typedef struct _GstVaapiDecoderH264 GstVaapiDecoderH264;
/**
* GstVaapiStreamAlignH264:
* @GST_VAAPI_STREAM_ALIGN_H264_NONE: Generic H.264 stream buffers
* @GST_VAAPI_STREAM_ALIGN_H264_NALU: H.264 stream buffers aligned NAL
* unit boundaries
* @GST_VAAPI_STREAM_ALIGN_H264_AU: H.264 stream buffers aligned on
* access unit boundaries
*
* Set of possible buffer alignments for H.264 streams.
*/
typedef enum {
GST_VAAPI_STREAM_ALIGN_H264_NONE,
GST_VAAPI_STREAM_ALIGN_H264_NALU,
GST_VAAPI_STREAM_ALIGN_H264_AU
} GstVaapiStreamAlignH264;
GstVaapiDecoder *
gst_vaapi_decoder_h264_new(GstVaapiDisplay *display, GstCaps *caps);
void
gst_vaapi_decoder_h264_set_alignment(GstVaapiDecoderH264 *decoder,
GstVaapiStreamAlignH264 alignment);
G_END_DECLS
#endif /* GST_VAAPI_DECODER_H264_H */

18
gst/vaapi/gstvaapidecode.c
View file

@ -644,6 +644,24 @@ gst_vaapidecode_create(GstVaapiDecode *decode, GstCaps *caps)
break;
case GST_VAAPI_CODEC_H264:
decode->decoder = gst_vaapi_decoder_h264_new(dpy, caps);
/* Set the stream buffer alignment for better optimizations */
if (decode->decoder && caps) {
GstStructure * const structure = gst_caps_get_structure(caps, 0);
const gchar *str = NULL;
if ((str = gst_structure_get_string(structure, "alignment"))) {
GstVaapiStreamAlignH264 alignment;
if (g_strcmp0(str, "au") == 0)
alignment = GST_VAAPI_STREAM_ALIGN_H264_AU;
else if (g_strcmp0(str, "nal") == 0)
alignment = GST_VAAPI_STREAM_ALIGN_H264_NALU;
else
alignment = GST_VAAPI_STREAM_ALIGN_H264_NONE;
gst_vaapi_decoder_h264_set_alignment(
GST_VAAPI_DECODER_H264(decode->decoder), alignment);
}
}
break;
case GST_VAAPI_CODEC_WMV3:
case GST_VAAPI_CODEC_VC1: