gstreamer/sys/vdpau/h264/gstnalreader.c

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2010-06-10 10:13:50 +00:00
/* GStreamer
*
* Copyright (C) 2009 Carl-Anton Ingmarsson <ca.ingmarsson@gmail.com>.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "gstnalreader.h"
static gboolean gst_nal_reader_read (GstNalReader * reader, guint nbits);
/**
* SECTION:gstnalreader
* @short_description: Bit reader which automatically skips
* emulation_prevention bytes
*
* #GstNalReader provides a bit reader which automatically skips
* emulation_prevention bytes. It provides functions for reading any number of bits
* into 8, 16, 32 and 64 bit variables. It also provides functions for reading
* Exp-Golomb values.
*/
/**
* gst_nal_reader_new:
* @data: Data from which the #GstNalReader should read
* @size: Size of @data in bytes
*
* Create a new #GstNalReader instance, which will read from @data.
*
* Returns: a new #GstNalReader instance
*
* Since: 0.10.22
*/
GstNalReader *
gst_nal_reader_new (const guint8 * data, guint size)
{
GstNalReader *ret = g_slice_new0 (GstNalReader);
ret->data = data;
ret->size = size;
ret->first_byte = 0xff;
ret->cache = 0xff;
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return ret;
}
/**
* gst_nal_reader_new_from_buffer:
* @buffer: Buffer from which the #GstNalReader should read
*
* Create a new #GstNalReader instance, which will read from the
* #GstBuffer @buffer.
*
* Returns: a new #GstNalReader instance
*
* Since: 0.10.22
*/
GstNalReader *
gst_nal_reader_new_from_buffer (const GstBuffer * buffer)
{
g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
return gst_nal_reader_new (GST_BUFFER_DATA (buffer),
GST_BUFFER_SIZE (buffer));
}
/**
* gst_nal_reader_free:
* @reader: a #GstNalReader instance
*
* Frees a #GstNalReader instance, which was previously allocated by
* gst_nal_reader_new() or gst_nal_reader_new_from_buffer().
*
* Since: 0.10.22
*/
void
gst_nal_reader_free (GstNalReader * reader)
{
g_return_if_fail (reader != NULL);
g_slice_free (GstNalReader, reader);
}
/**
* gst_nal_reader_init:
* @reader: a #GstNalReader instance
* @data: Data from which the #GstNalReader should read
* @size: Size of @data in bytes
*
* Initializes a #GstNalReader instance to read from @data. This function
* can be called on already initialized instances.
*
* Since: 0.10.22
*/
void
gst_nal_reader_init (GstNalReader * reader, const guint8 * data, guint size)
{
g_return_if_fail (reader != NULL);
reader->data = data;
reader->size = size;
reader->byte = 0;
reader->bits_in_cache = 0;
/* fill with something other than 0 to detect emulation prevention bytes */
reader->first_byte = 0xff;
reader->cache = 0xff;
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}
/**
* gst_nal_reader_init_from_buffer:
* @reader: a #GstNalReader instance
* @buffer: Buffer from which the #GstNalReader should read
*
* Initializes a #GstNalReader instance to read from @buffer. This function
* can be called on already initialized instances.
*
* Since: 0.10.22
*/
void
gst_nal_reader_init_from_buffer (GstNalReader * reader,
const GstBuffer * buffer)
{
g_return_if_fail (GST_IS_BUFFER (buffer));
gst_nal_reader_init (reader, GST_BUFFER_DATA (buffer),
GST_BUFFER_SIZE (buffer));
}
/**
* gst_nal_reader_skip:
* @reader: a #GstNalReader instance
* @nbits: the number of bits to skip
*
* Skips @nbits bits of the #GstNalReader instance.
*
* Returns: %TRUE if @nbits bits could be skipped, %FALSE otherwise.
*
* Since: 0.10.22
*/
gboolean
gst_nal_reader_skip (GstNalReader * reader, guint nbits)
{
g_return_val_if_fail (reader != NULL, FALSE);
if (G_UNLIKELY (!gst_nal_reader_read (reader, nbits)))
return FALSE;
reader->bits_in_cache -= nbits;
return TRUE;
}
/**
* gst_nal_reader_skip_to_byte:
* @reader: a #GstNalReader instance
*
* Skips until the next byte.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
gboolean
gst_nal_reader_skip_to_byte (GstNalReader * reader)
{
g_return_val_if_fail (reader != NULL, FALSE);
if (reader->bits_in_cache == 0) {
if (G_LIKELY ((reader->size - reader->byte) > 0))
reader->byte++;
else
return FALSE;
}
reader->bits_in_cache = 0;
return TRUE;
}
/**
* gst_nal_reader_get_pos:
* @reader: a #GstNalReader instance
*
* Returns the current position of a GstNalReader instance in bits.
*
* Returns: The current position in bits
*
*/
guint
gst_nal_reader_get_pos (const GstNalReader * reader)
{
return reader->byte * 8 - reader->bits_in_cache;
}
/**
* gst_nal_reader_get_remaining:
* @reader: a #GstNalReader instance
*
* Returns the remaining number of bits of a GstNalReader instance.
*
* Returns: The remaining number of bits.
*
*/
guint
gst_nal_reader_get_remaining (const GstNalReader * reader)
{
return (reader->size - reader->byte) * 8 + reader->bits_in_cache;
}
/**
* gst_nal_reader_get_bits_uint8:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint8 to store the result
* @nbits: number of bits to read
*
* Read @nbits bits into @val and update the current position.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
/**
* gst_nal_reader_get_bits_uint16:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint16 to store the result
* @nbits: number of bits to read
*
* Read @nbits bits into @val and update the current position.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
/**
* gst_nal_reader_get_bits_uint32:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint32 to store the result
* @nbits: number of bits to read
*
* Read @nbits bits into @val and update the current position.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
/**
* gst_nal_reader_get_bits_uint64:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint64 to store the result
* @nbits: number of bits to read
*
* Read @nbits bits into @val and update the current position.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
/**
* gst_nal_reader_peek_bits_uint8:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint8 to store the result
* @nbits: number of bits to read
*
* Read @nbits bits into @val but keep the current position.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
/**
* gst_nal_reader_peek_bits_uint16:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint16 to store the result
* @nbits: number of bits to read
*
* Read @nbits bits into @val but keep the current position.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
/**
* gst_nal_reader_peek_bits_uint32:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint32 to store the result
* @nbits: number of bits to read
*
* Read @nbits bits into @val but keep the current position.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
/**
* gst_nal_reader_peek_bits_uint64:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint64 to store the result
* @nbits: number of bits to read
*
* Read @nbits bits into @val but keep the current position.
*
* Returns: %TRUE if successful, %FALSE otherwise.
*
* Since: 0.10.22
*/
static gboolean
gst_nal_reader_read (GstNalReader * reader, guint nbits)
{
if (G_UNLIKELY (reader->byte * 8 + (nbits - reader->bits_in_cache) >
reader->size * 8))
return FALSE;
while (reader->bits_in_cache < nbits) {
guint8 byte;
gboolean check_three_byte;
check_three_byte = TRUE;
next_byte:
if (G_UNLIKELY (reader->byte >= reader->size))
return FALSE;
byte = reader->data[reader->byte++];
/* check if the byte is a emulation_prevention_three_byte */
if (check_three_byte && byte == 0x03 && reader->first_byte == 0x00 &&
((reader->cache & 0xff) == 0)) {
/* next byte goes unconditionally to the cache, even if it's 0x03 */
check_three_byte = FALSE;
goto next_byte;
}
reader->cache = (reader->cache << 8) | reader->first_byte;
reader->first_byte = byte;
reader->bits_in_cache += 8;
}
return TRUE;
}
#define GST_NAL_READER_READ_BITS(bits) \
gboolean \
gst_nal_reader_get_bits_uint##bits (GstNalReader *reader, guint##bits *val, guint nbits) \
{ \
guint shift; \
\
g_return_val_if_fail (reader != NULL, FALSE); \
g_return_val_if_fail (val != NULL, FALSE); \
g_return_val_if_fail (nbits <= bits, FALSE); \
\
if (!gst_nal_reader_read (reader, nbits)) \
return FALSE; \
\
/* bring the required bits down and truncate */ \
shift = reader->bits_in_cache - nbits; \
*val = reader->first_byte >> shift; \
\
*val |= reader->cache << (8 - shift); \
/* mask out required bits */ \
if (nbits < bits) \
*val &= ((guint##bits)1 << nbits) - 1; \
\
reader->bits_in_cache = shift; \
\
return TRUE; \
} \
\
gboolean \
gst_nal_reader_peek_bits_uint##bits (const GstNalReader *reader, guint##bits *val, guint nbits) \
{ \
GstNalReader tmp; \
\
g_return_val_if_fail (reader != NULL, FALSE); \
tmp = *reader; \
return gst_nal_reader_get_bits_uint##bits (&tmp, val, nbits); \
}
GST_NAL_READER_READ_BITS (8);
GST_NAL_READER_READ_BITS (16);
GST_NAL_READER_READ_BITS (32);
GST_NAL_READER_READ_BITS (64);
/**
* gst_nal_reader_get_ue:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint32 to store the result
*
* Reads an unsigned Exp-Golomb value into val
*
* Returns: %TRUE if successful, %FALSE otherwise.
*/
gboolean
gst_nal_reader_get_ue (GstNalReader * reader, guint32 * val)
{
guint i = 0;
guint8 bit;
guint32 value;
if (G_UNLIKELY (!gst_nal_reader_get_bits_uint8 (reader, &bit, 1)))
return FALSE;
while (bit == 0) {
i++;
if G_UNLIKELY
((!gst_nal_reader_get_bits_uint8 (reader, &bit, 1)))
return FALSE;
}
g_return_val_if_fail (i <= 32, FALSE);
if (G_UNLIKELY (!gst_nal_reader_get_bits_uint32 (reader, &value, i)))
return FALSE;
*val = (1 << i) - 1 + value;
return TRUE;
}
/**
* gst_nal_reader_peek_ue:
* @reader: a #GstNalReader instance
* @val: Pointer to a #guint32 to store the result
*
* Read an unsigned Exp-Golomb value into val but keep the current position
*
* Returns: %TRUE if successful, %FALSE otherwise.
*/
gboolean
gst_nal_reader_peek_ue (const GstNalReader * reader, guint32 * val)
{
GstNalReader tmp;
g_return_val_if_fail (reader != NULL, FALSE);
tmp = *reader;
return gst_nal_reader_get_ue (&tmp, val);
}
/**
* gst_nal_reader_get_se:
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* @reader: a #GstNalReader instance
* @val: Pointer to a #gint32 to store the result
*
* Reads a signed Exp-Golomb value into val
*
* Returns: %TRUE if successful, %FALSE otherwise.
*/
gboolean
gst_nal_reader_get_se (GstNalReader * reader, gint32 * val)
{
guint32 value;
if (G_UNLIKELY (!gst_nal_reader_get_ue (reader, &value)))
return FALSE;
if (value % 2)
*val = (value / 2) + 1;
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else
*val = -(value / 2);
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return TRUE;
}
/**
* gst_nal_reader_peek_se:
* @reader: a #GstNalReader instance
* @val: Pointer to a #gint32 to store the result
*
* Read a signed Exp-Golomb value into val but keep the current position
*
* Returns: %TRUE if successful, %FALSE otherwise.
*/
gboolean
gst_nal_reader_peek_se (const GstNalReader * reader, gint32 * val)
{
GstNalReader tmp;
g_return_val_if_fail (reader != NULL, FALSE);
tmp = *reader;
return gst_nal_reader_get_se (&tmp, val);
}