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codecparsers: h264: add nal_reader_skip_long() helper.

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Add nal_reader_skip_long() helper function to allow an arbitrary number
of bits to be skipped. The former nal_reader_skip() function is too
limited to the actual cache size.

Use this new function to simplify gst_h264_parser_parse_sei_message()
default case, that skips unsupported payloads.

v2: made args consistent from header to source file.

Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
This commit is contained in:
Gwenole Beauchesne 2014-03-25 12:01:55 +01:00
parent 2e83aca728
commit 0440cabf49
3 changed files with 26 additions and 8 deletions
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11
gst-libs/gst/codecparsers/gsth264parser.c
View file

@ -893,18 +893,13 @@ gst_h264_parser_parse_sei_message (GstH264NalParser * nalparser,
res = gst_h264_parser_parse_pic_timing (nalparser,
&sei->payload.pic_timing, nr);
break;
default:{
default:
/* Just consume payloadSize bytes, which does not account for
emulation prevention bytes */
guint nbits = payload_size % 8;
while (payload_size > 0) {
nal_reader_skip (nr, nbits);
payload_size -= nbits;
nbits = 8;
}
if (!nal_reader_skip_long (nr, payload_size))
goto error;
res = GST_H264_PARSER_OK;
break;
}
}
/* When SEI message doesn't end at byte boundary,

22
gst-libs/gst/codecparsers/nalutils.c
View file

@ -113,9 +113,13 @@ nal_reader_read (NalReader * nr, guint nbits)
return TRUE;
}
/* Skips the specified amount of bits. This is only suitable to a
cacheable number of bits */
inline gboolean
nal_reader_skip (NalReader * nr, guint nbits)
{
g_assert (nbits <= 8 * sizeof (nr->cache));
if (G_UNLIKELY (!nal_reader_read (nr, nbits)))
return FALSE;
@ -124,6 +128,24 @@ nal_reader_skip (NalReader * nr, guint nbits)
return TRUE;
}
/* Generic version to skip any number of bits */
gboolean
nal_reader_skip_long (NalReader * nr, guint nbits)
{
/* Leave out enough bits in the cache once we are finished */
const guint skip_size = 4 * sizeof (nr->cache);
guint remaining = nbits;
nbits %= skip_size;
while (remaining > 0) {
if (!nal_reader_skip (nr, nbits))
return FALSE;
remaining -= nbits;
nbits = skip_size;
}
return TRUE;
}
inline guint
nal_reader_get_pos (const NalReader * nr)
{

1
gst-libs/gst/codecparsers/nalutils.h
View file

@ -57,6 +57,7 @@ void nal_reader_init (NalReader * nr, const guint8 * data, guint size);
gboolean nal_reader_read (NalReader * nr, guint nbits);
gboolean nal_reader_skip (NalReader * nr, guint nbits);
gboolean nal_reader_skip_long (NalReader * nr, guint nbits);
guint nal_reader_get_pos (const NalReader * nr);
guint nal_reader_get_remaining (const NalReader * nr);
guint nal_reader_get_epb_count (const NalReader * nr);