Compressed stream support

Compressed stream support. More...

Data Structures

struct  gavl_compression_info_t
 Compression format. More...
struct  gavl_packet_t
 Packet structure. More...

Defines

#define GAVL_COMPRESSION_HAS_P_FRAMES   (1<<0)
 Set if not all frames are keyframes.
#define GAVL_COMPRESSION_HAS_B_FRAMES   (1<<1)
 Set if frames don't appear in presentation order.
#define GAVL_COMPRESSION_HAS_FIELD_PICTURES   (1<<2)
 Packets can consist of 2 consecutive fields.
#define GAVL_COMPRESSION_SBR   (1<<3)
 Samplerate got doubled by decoder, format and sample counts are for the upsampled rate.
#define GAVL_COMPRESSION_BIG_ENDIAN   (1<<4)
 Only in uncompressed gavf streams: Specifies that multibyte numbers are big endian.
#define GAVL_BITRATE_VBR   -1
 Use this to specify a VBR stream.
#define GAVL_BITRATE_LOSSLESS   -2
 Use this to specify a losslessly compressed stream.
#define GAVL_PACKET_TYPE_I   0x01
 Packet is an I-frame.
#define GAVL_PACKET_TYPE_P   0x02
 Packet is a P-frame.
#define GAVL_PACKET_TYPE_B   0x03
 Packet is a B-frame.
#define GAVL_PACKET_TYPE_MASK   0x03
 Mask for frame type.
#define GAVL_PACKET_KEYFRAME   (1<<2)
 Packet is a keyframe.
#define GAVL_PACKET_LAST   (1<<3)
 Packet is the last in the stream (only Xiph codecs need this flag).
#define GAVL_PACKET_EXT   (1<<4)
 Packet has extensions (used only in gavf files).
#define GAVL_PACKET_REF   (1<<5)
 B-frame used as reference (can't savely be skipped).
#define GAVL_PACKET_NOOUTPUT   (1<<6)
 Packet will produce no decoder output (e.g. VP8 alternate reference).
#define GAVL_PACKET_PADDING   32
 Packets are padded with this many zero bytes.

Enumerations

enum  gavl_codec_id_t {
  GAVL_CODEC_ID_NONE = 0,
  GAVL_CODEC_ID_ALAW = 1,
  GAVL_CODEC_ID_ULAW,
  GAVL_CODEC_ID_MP2,
  GAVL_CODEC_ID_MP3,
  GAVL_CODEC_ID_AC3,
  GAVL_CODEC_ID_AAC,
  GAVL_CODEC_ID_VORBIS,
  GAVL_CODEC_ID_FLAC,
  GAVL_CODEC_ID_OPUS,
  GAVL_CODEC_ID_SPEEX,
  GAVL_CODEC_ID_DTS,
  GAVL_CODEC_ID_JPEG = 0x10000,
  GAVL_CODEC_ID_PNG,
  GAVL_CODEC_ID_TIFF,
  GAVL_CODEC_ID_TGA,
  GAVL_CODEC_ID_MPEG1,
  GAVL_CODEC_ID_MPEG2,
  GAVL_CODEC_ID_MPEG4_ASP,
  GAVL_CODEC_ID_H264,
  GAVL_CODEC_ID_THEORA,
  GAVL_CODEC_ID_DIRAC,
  GAVL_CODEC_ID_DV,
  GAVL_CODEC_ID_VP8,
  GAVL_CODEC_ID_DIV3,
  GAVL_CODEC_ID_DVDSUB = 0x20000
}
 Codec ID. More...

Functions

void gavl_compression_info_init (gavl_compression_info_t *info)
 Initialize a compression info.
GAVL_PUBLIC void gavl_compression_info_free (gavl_compression_info_t *info)
 Free all dynamically allocated memory of a compression info.
GAVL_PUBLIC void gavl_compression_info_dump (const gavl_compression_info_t *info)
 Dump a compression info to stderr.
GAVL_PUBLIC void gavl_compression_info_dumpi (const gavl_compression_info_t *info, int num)
 Dump a compression info to stderr.
GAVL_PUBLIC void gavl_compression_info_copy (gavl_compression_info_t *dst, const gavl_compression_info_t *src)
 Copy a compression info.
GAVL_PUBLIC void gavl_append_xiph_header (uint8_t **global_header, int *global_header_len, uint8_t *header, int header_len)
 Append a Xiph packet to a global header.
GAVL_PUBLIC uint8_t * gavl_extract_xiph_header (uint8_t *global_header, int global_header_len, int idx, int *header_len)
 Extract a Xiph packet to a global header.
GAVL_PUBLIC const char * gavl_compression_get_extension (gavl_codec_id_t id, int *separate)
 Get the file extension of the corresponding raw format.
GAVL_PUBLIC int gavl_compression_need_pixelformat (gavl_codec_id_t id)
 Check if the compression supports multiple pixelformats.
const char * gavl_compression_get_mimetype (const gavl_compression_info_t *ci)
 Get the mimetype for the corresponding elementary format.
GAVL_PUBLIC int gavl_compression_constant_frame_samples (gavl_codec_id_t id)
 Check if an audio compression constant frame samples.
GAVL_PUBLIC int gavl_compression_get_sample_size (gavl_codec_id_t id)
 Check if an audio compression size for each samples.
GAVL_PUBLIC const char * gavl_compression_get_long_name (gavl_codec_id_t id)
 Return the long name of the compression.
GAVL_PUBLIC const char * gavl_compression_get_short_name (gavl_codec_id_t id)
 Return the short name of the compression.
GAVL_PUBLIC gavl_codec_id_t gavl_compression_from_short_name (const char *name)
 Get a compression from the short name.
GAVL_PUBLIC int gavl_num_compressions ()
 Get the number of compression formats.
GAVL_PUBLIC gavl_codec_id_t gavl_get_compression (int index)
 Get a compression format for a specified index.
GAVL_PUBLIC void gavl_packet_init (gavl_packet_t *p)
 Initialize a packet.
GAVL_PUBLIC void gavl_packet_alloc (gavl_packet_t *p, int len)
 Allocate memory for a packet.
GAVL_PUBLIC void gavl_packet_free (gavl_packet_t *p)
 Free memory of a packet.
GAVL_PUBLIC void gavl_packet_copy (gavl_packet_t *dst, const gavl_packet_t *src)
 Copy a packet.
GAVL_PUBLIC void gavl_packet_copy_metadata (gavl_packet_t *dst, const gavl_packet_t *src)
 Copy metadata of a packet.
GAVL_PUBLIC void gavl_packet_reset (gavl_packet_t *p)
 Reset a packet.
GAVL_PUBLIC void gavl_packet_dump (const gavl_packet_t *p)
 Dump a packet to stderr.
GAVL_PUBLIC void gavl_packet_save (const gavl_packet_t *p, const char *filename)
 Save a packet to a file.

Detailed Description

Compressed stream support.

gavl provides some structures and functions for handling compressed data packets. It is a completely independent API layer and has nothing to do with the uncompressed video and audio API. In particular the conversion between compressed and uncompressed data (i.e. codecs) are outside the scope of gavl. These are implemented in gmerlin-avdecoder and gmerlin encoding plugins.


Define Documentation

#define GAVL_COMPRESSION_HAS_P_FRAMES   (1<<0)

Set if not all frames are keyframes.

#define GAVL_COMPRESSION_HAS_B_FRAMES   (1<<1)

Set if frames don't appear in presentation order.

#define GAVL_COMPRESSION_HAS_FIELD_PICTURES   (1<<2)

Packets can consist of 2 consecutive fields.

#define GAVL_COMPRESSION_SBR   (1<<3)

Samplerate got doubled by decoder, format and sample counts are for the upsampled rate.

#define GAVL_COMPRESSION_BIG_ENDIAN   (1<<4)

Only in uncompressed gavf streams: Specifies that multibyte numbers are big endian.

#define GAVL_BITRATE_VBR   -1

Use this to specify a VBR stream.

#define GAVL_BITRATE_LOSSLESS   -2

Use this to specify a losslessly compressed stream.

#define GAVL_PACKET_TYPE_I   0x01

Packet is an I-frame.

#define GAVL_PACKET_TYPE_P   0x02

Packet is a P-frame.

#define GAVL_PACKET_TYPE_B   0x03

Packet is a B-frame.

#define GAVL_PACKET_TYPE_MASK   0x03

Mask for frame type.

#define GAVL_PACKET_KEYFRAME   (1<<2)

Packet is a keyframe.

#define GAVL_PACKET_LAST   (1<<3)

Packet is the last in the stream (only Xiph codecs need this flag).

#define GAVL_PACKET_EXT   (1<<4)

Packet has extensions (used only in gavf files).

#define GAVL_PACKET_REF   (1<<5)

B-frame used as reference (can't savely be skipped).

#define GAVL_PACKET_NOOUTPUT   (1<<6)

Packet will produce no decoder output (e.g. VP8 alternate reference).

#define GAVL_PACKET_PADDING   32

Packets are padded with this many zero bytes.


Enumeration Type Documentation

Codec ID.

These are used as identifiers for the type of compression

Enumerator:
GAVL_CODEC_ID_NONE  Unknown/unsupported compression format. In gavf files this signals that the stream consists of uncompressed gavl frames.
GAVL_CODEC_ID_ALAW  alaw 2:1
GAVL_CODEC_ID_ULAW  mu-law 2:1
GAVL_CODEC_ID_MP2  MPEG-1 audio layer II.
GAVL_CODEC_ID_MP3  MPEG-1/2 audio layer 3 CBR/VBR.
GAVL_CODEC_ID_AC3  AC3.
GAVL_CODEC_ID_AAC  AAC as stored in quicktime/mp4.
GAVL_CODEC_ID_VORBIS  Vorbis (segmented extradata and packets).
GAVL_CODEC_ID_FLAC  Flac (extradata contain a file header without comment and seektable).
GAVL_CODEC_ID_OPUS  Opus.
GAVL_CODEC_ID_SPEEX  Speex.
GAVL_CODEC_ID_DTS  DTS.
GAVL_CODEC_ID_JPEG  JPEG image.
GAVL_CODEC_ID_PNG  PNG image.
GAVL_CODEC_ID_TIFF  TIFF image.
GAVL_CODEC_ID_TGA  TGA image.
GAVL_CODEC_ID_MPEG1  MPEG-1 video.
GAVL_CODEC_ID_MPEG2  MPEG-2 video.
GAVL_CODEC_ID_MPEG4_ASP  MPEG-4 ASP (a.k.a. Divx4).
GAVL_CODEC_ID_H264  H.264 (Annex B).
GAVL_CODEC_ID_THEORA  Theora (segmented extradata).
GAVL_CODEC_ID_DIRAC  Complete DIRAC frames, sequence end code appended to last packet.
GAVL_CODEC_ID_DV  DV (several variants).
GAVL_CODEC_ID_VP8  VP8 (as used in webm).
GAVL_CODEC_ID_DIV3  Old style Divx (aka MSMPEG4V3).
GAVL_CODEC_ID_DVDSUB  DVD subtitles, palette is in header.


Function Documentation

void gavl_compression_info_init ( gavl_compression_info_t info  ) 

Initialize a compression info.

Parameters:
info A compression info
Use this for compression infos which are on the stack before using them.

GAVL_PUBLIC void gavl_compression_info_free ( gavl_compression_info_t info  ) 

Free all dynamically allocated memory of a compression info.

Parameters:
info A compression info

GAVL_PUBLIC void gavl_compression_info_dump ( const gavl_compression_info_t info  ) 

Dump a compression info to stderr.

Parameters:
info A compression info
Use this for debugging

GAVL_PUBLIC void gavl_compression_info_dumpi ( const gavl_compression_info_t info,
int  num 
)

Dump a compression info to stderr.

Parameters:
info A compression info
indent Indentation
Same as gavl_compression_info_dump but it puts indent whitespaces in front of each line.

GAVL_PUBLIC void gavl_compression_info_copy ( gavl_compression_info_t dst,
const gavl_compression_info_t src 
)

Copy a compression info.

Parameters:
dst Destination
src Source

GAVL_PUBLIC void gavl_append_xiph_header ( uint8_t **  global_header,
int *  global_header_len,
uint8_t *  header,
int  header_len 
)

Append a Xiph packet to a global header.

Parameters:
global_header Global header (will be changed)
global_header_len Global header length (will be changed)
header header to append
header_len length of header to append

GAVL_PUBLIC uint8_t* gavl_extract_xiph_header ( uint8_t *  global_header,
int  global_header_len,
int  idx,
int *  header_len 
)

Extract a Xiph packet to a global header.

Parameters:
global_header Global header
global_header_len Global header length
idx Index of the packet (starting with 0)
header_len Returns the length of the header
Returns:
The data of the header packet

GAVL_PUBLIC const char* gavl_compression_get_extension ( gavl_codec_id_t  id,
int *  separate 
)

Get the file extension of the corresponding raw format.

Parameters:
id A codec ID
separate If non-null returns 1 if each packet should be in a separate file
Returns:
The file extension of the raw file or NULL
This function can be used for writing elementary streams to files. It returns a suitable file extension. If separate is 1, each packet should be written to a separate file. This basically means, that the codec corresponds to an image format.

Not all compression formats have a suitable elementary stream format, in this case NULL is returned for the extension. Most prominent examples are Vorbis and Theora, which can hardly exist outside an OGG container.

GAVL_PUBLIC int gavl_compression_need_pixelformat ( gavl_codec_id_t  id  ) 

Check if the compression supports multiple pixelformats.

Parameters:
id A codec ID
Returns:
1 if the compression ID must be associated with a pixelformat, 0 else
This function can be used by decoding libraries to check if the compresison ID is sufficient or if the pixelformat must be valid in the associated video format.

const char* gavl_compression_get_mimetype ( const gavl_compression_info_t ci  ) 

Get the mimetype for the corresponding elementary format.

Parameters:
ci A compression info
Returns:
The mimetype (can be NULL)

GAVL_PUBLIC int gavl_compression_constant_frame_samples ( gavl_codec_id_t  id  ) 

Check if an audio compression constant frame samples.

Parameters:
id A codec ID
Returns:
1 if the compression has the same number of samples in each frame, 0 else

GAVL_PUBLIC int gavl_compression_get_sample_size ( gavl_codec_id_t  id  ) 

Check if an audio compression size for each samples.

Parameters:
id A codec ID
Returns:
The coded size of one sample or 0

GAVL_PUBLIC const char* gavl_compression_get_long_name ( gavl_codec_id_t  id  ) 

Return the long name of the compression.

Parameters:
id A codec ID
Returns:
The long name or NULL

GAVL_PUBLIC const char* gavl_compression_get_short_name ( gavl_codec_id_t  id  ) 

Return the short name of the compression.

Parameters:
id A codec ID
Returns:
The short name or NULL

GAVL_PUBLIC gavl_codec_id_t gavl_compression_from_short_name ( const char *  name  ) 

Get a compression from the short name.

Parameters:
A short name
Returns:
The codec ID (or GAVL_CODEC_ID_NONE)

GAVL_PUBLIC int gavl_num_compressions (  ) 

Get the number of compression formats.

Returns:
The number of supported compresion formats
Use this with gavl_get_compression to enumerate all compression formats

GAVL_PUBLIC gavl_codec_id_t gavl_get_compression ( int  index  ) 

Get a compression format for a specified index.

Parameters:
index Index (starting with 0)
Returns:
The compression format
Use this with gavl_num_compressions to enumerate all compression formats

GAVL_PUBLIC void gavl_packet_init ( gavl_packet_t p  ) 

Initialize a packet.

Parameters:
p A packet

GAVL_PUBLIC void gavl_packet_alloc ( gavl_packet_t p,
int  len 
)

Allocate memory for a packet.

Parameters:
p A packet
len Number of bytes you want to store in the packet
This function uses realloc(), which means that it preserves the data already contained in the packet.

GAVL_PUBLIC void gavl_packet_free ( gavl_packet_t p  ) 

Free memory of a packet.

Parameters:
p A packet

GAVL_PUBLIC void gavl_packet_copy ( gavl_packet_t dst,
const gavl_packet_t src 
)

Copy a packet.

Parameters:
dst Destination
src Source

GAVL_PUBLIC void gavl_packet_copy_metadata ( gavl_packet_t dst,
const gavl_packet_t src 
)

Copy metadata of a packet.

Parameters:
dst Destination
src Source
Like gavl_packet_copy but leaves the payload of dst untouched.

Since 1.5.0

GAVL_PUBLIC void gavl_packet_reset ( gavl_packet_t p  ) 

Reset a packet.

Parameters:
p Destination
Set fields to their default values

GAVL_PUBLIC void gavl_packet_dump ( const gavl_packet_t p  ) 

Dump a packet to stderr.

Parameters:
p A packet
Use this for debugging

GAVL_PUBLIC void gavl_packet_save ( const gavl_packet_t p,
const char *  filename 
)

Save a packet to a file.

Parameters:
p A packet
file Filename
Use this for debugging


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