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音视频图像编解码

 
阅读更多
写道
图像处理
https://www.iteye.com/blog/lobin-2508589

 

写道
音视频处理
https://www.iteye.com/blog/lobin-2439912

 

音视频编解码

离散傅立叶变换



根据殴拉公式，离散傅立叶变换还可以写成以下形式。

 

殴拉公式

 

 

 

其中∑表示求和，读作"sigma"。

 

 

∑求和的例子

求矩形面积

 

 

 

∑求和的例子

求圆面积

 

 

 

 

 

编码格式

MPEG

 

MPEG1

 

MPEG2

 

MPEG4

 

Part 2: Visual

 

 

写道
* ——————————————————————————————————————————————————————————————+—————————————+—————————
* VisualObjectSequence() { | No. of bits | Mnemonic
* do { | |
* visual_object_sequence_start_code | 32 | bslbf
* profile_and_level_indication | 8 | uimsbf
* while ( next_bits()== user_data_start_code){ | |
* user_data() | |
* } | |
* VisualObject() | |
* } while ( next_bits() != visual_object_sequence_end_code) | |
* visual_object_sequence_end_code | 32 | bslbf
* } | |
* ——————————————————————————————————————————————————————————————+—————————————+—————————
* 
* User data
* ——————————————————————————————————————————————————————————————+—————————————+—————————
* user_data() { | No. of bits | Mnemonic
* user_data_start_code | 32 | bslbf
* while( next_bits() != ‘0000 0000 0000 0000 0000 0001’ ) { | |
* user_data | 8 | uimsbf
* } | |
* } | |
* ——————————————————————————————————————————————————————————————+—————————————+—————————

 

 

写道
* —————————————————————————————————————————————————————————————————————————————————+—————————————+—————————
* VisualObject() { | No. of bits | Mnemonic
* visual_object_start_code | 32 | bslbf
* is_visual_object_identifier | 1 | uimsbf
* if (is_visual_object_identifier) { | |
* visual_object_verid | 4 | uimsbf
* visual_object_priority | 3 | uimsbf
* } | |
* visual_object_type | 4 | uimsbf
* if (visual_object_type == “video ID” || visual_object_type == “still texture | |
* ID“) { | |
* video_signal_type() | |
* } | |
* next_start_code() | |
* while ( next_bits()== user_data_start_code){ | |
* user_data() | |
* } | |
* if (visual_object_type == “video ID”) { | |
* video_object_start_code | 32 | bslbf
* VideoObjectLayer() | |
* } | |
* else if (visual_object_type == “still texture ID”) { | |
* StillTextureObject() | |
* } | |
* else if (visual_object_type == “mesh ID”) { | |
* MeshObject() | |
* } | |
* else if (visual_object_type == “FBA ID”) { | |
* FBAObject() | |
* } | |
* else if (visual_object_type == “3D mesh ID”) { | |
* 3D_Mesh_Object() | |
* } | |
* if (next_bits() != “0000 0000 0000 0000 0000 0001”) | |
* next_start_code() | |
* } | |
* —————————————————————————————————————————————————————————————————————————————————+—————————————+—————————

 

 

写道
* ——————————————————————————————————————————————————————————————+—————————————+—————————
* video_signal_type() { | No. of bits | Mnemonic
* video_signal_type | 1 | bslbf
* if (video_signal_type) { | |
* video_format | 3 | uimsbf
* video_range | 1 | bslbf
* colour_description | 1 | bslbf
* if (colour_description) { | |
* colour_primaries | 8 | uimsbf
* transfer_characteristics | 8 | uimsbf
* matrix_coefficients | 8 | uimsbf
* } | |
* } | |
* } | |
* ——————————————————————————————————————————————————————————————+—————————————+—————————

 

 

 

ASF

ASF对象

ASF对象全局唯一ID（GUID）

  // Top-level ASF object GUIDS
  {
    "75B22630-668E-11CF-A6D9-00AA0062CE6C", 
    "ASF_Header_Object"
  }, {
    "75B22636-668E-11CF-A6D9-00AA0062CE6C", 
    "ASF_Data_Object"
  }, {
    "33000890-E5B1-11CF-89F4-00A0C90349CB", 
    "ASF_Simple_Index_Object"
  }, {
    "D6E229D3-35DA-11D1-9034-00A0C90349BE", 
    "ASF_Index_Object"
  }, {
    "FEB103F8-12AD-4C64-840F-2A1D2F7AD48C", 
    "ASF_Media_Object_Index_Object"
  }, {
    "3CB73FD0-0C4A-4803-953D-EDF7B6228F0C", 
    "ASF_Timecode_Index_Object"
  }, 
  
  // Header Object GUIDs
  {
    "8CABDCA1-A947-11CF-8EE4-00C00C205365", 
    "ASF_File_Properties_Object"
  }, {
    "B7DC0791-A9B7-11CF-8EE6-00C00C205365", 
    "ASF_Stream_Properties_Object"
  }, {
    "5FBF03B5-A92E-11CF-8EE3-00C00C205365", 
    "ASF_Header_Extension_Object"
  }, {
    "86D15240-311D-11D0-A3A4-00A0C90348F6", 
    "ASF_Codec_List_Object"
  }, {
    "1EFB1A30-0B62-11D0-A39B-00A0C90348F6", 
    "ASF_Script_Command_Object"
  }, {
    "F487CD01-A951-11CF-8EE6-00C00C205365", 
    "ASF_Marker_Object"
  }, {
    "D6E229DC-35DA-11D1-9034-00A0C90349BE", 
    "ASF_Bitrate_Mutual_Exclusion_Object"
  }, {
    "75B22635-668E-11CF-A6D9-00AA0062CE6C", 
    "ASF_Error_Correction_Object"
  }, {
    "75B22633-668E-11CF-A6D9-00AA0062CE6C", 
    "ASF_Content_Description_Object"
  }, {
    "D2D0A440-E307-11D2-97F0-00A0C95EA850", 
    "ASF_Extended_Content_Description_Object"
  }, {
    "2211B3FA-BD23-11D2-B4B7-00A0C955FC6E", 
    "ASF_Content_Branding_Object"
  }, {
    "7BF875CE-468D-11D1-8D82-006097C9A2B2", 
    "ASF_Stream_Bitrate_Properties_Object"
  }, {
    "2211B3FB-BD23-11D2-B4B7-00A0C955FC6E", 
    "ASF_Content_Encryption_Object"
  }, {
    "298AE614-2622-4C17-B935-DAE07EE9289C", 
    "ASF_Extended_Content_Encryption_Object"
  }, {
    "2211B3FC-BD23-11D2-B4B7-00A0C955FC6E", 
    "ASF_Digital_Signature_Object"
  }, {
    "1806D474-CADF-4509-A4BA-9AABCB96AAE8", 
    "ASF_Padding_Object"
  }, 
  
  // Header Extension Object GUIDs
  {
    "14E6A5CB-C672-4332-8399-A96952065B5A", 
    "ASF_Extended_Stream_Properties_Object"
  }, {
    "A08649CF-4775-4670-8A16-6E35357566CD", 
    "ASF_Advanced_Mutual_Exclusion_Object"
  }, {
    "D1465A40-5A79-4338-B71B-E36B8FD6C249", 
    "ASF_Group_Mutual_Exclusion_Object"
  }, {
    "D4FED15B-88D3-454F-81F0-ED5C45999E24", 
    "ASF_Stream_Prioritization_Object"
  }, {
    "A69609E6-517B-11D2-B6AF-00C04FD908E9", 
    "ASF_Bandwidth_Sharing_Object"
  }, {
    "7C4346A9-EFE0-4BFC-B229-393EDE415C85", 
    "ASF_Language_List_Object"
  }, {
    "C5F8CBEA-5BAF-4877-8467-AA8C44FA4CCA", 
    "ASF_Metadata_Object"
  }, {
    "44231C94-9498-49D1-A141-1D134E457054", 
    "ASF_Metadata_Library_Object"
  }, {
    "D6E229DF-35DA-11D1-9034-00A0C90349BE", 
    "ASF_Index_Parameters_Object"
  }, {
    "6B203BAD-3F11-48E4-ACA8-D7613DE2CFA7", 
    "ASF_Media_Object_Index_Parameters_Object"
  }, {
    "F55E496D-9797-4B5D-8C8B-604DFE9BFB24", 
    "ASF_Timecode_Index_Parameters_Object"
  }, {
    "75B22630-668E-11CF-A6D9-00AA0062CE6C", 
    "ASF_Compatibility_Object"
  }, {
    "43058533-6981-49E6-9B74-AD12CB86D58C", 
    "ASF_Advanced_Content_Encryption_Object"
  }, 
  
  // Stream Properties Object Stream Type GUIDs
  {
    "F8699E40-5B4D-11CF-A8FD-00805F5C442B", 
    "ASF_Audio_Media"
  }, {
    "BC19EFC0-5B4D-11CF-A8FD-00805F5C442B", 
    "ASF_Video_Media"
  }, {
    "59DACFC0-59E6-11D0-A3AC-00A0C90348F6", 
    "ASF_Command_Media"
  }, {
    "B61BE100-5B4E-11CF-A8FD-00805F5C442B", 
    "ASF_JFIF_Media"
  }, {
    "35907DE0-E415-11CF-A917-00805F5C442B", 
    "ASF_Degradable_JPEG_Media"
  }, {
    "91BD222C-F21C-497A-8B6D-5AA86BFC0185", 
    "ASF_File_Transfer_Media"
  }, {
    "3AFB65E2-47EF-40F2-AC2C-70A90D71D343", 
    "ASF_Binary_Media"
  }, 

  // Web stream Type-Specific Data GUIDs
  {
    "776257D4-C627-41CB-8F81-7AC7FF1C40CC", 
    "ASF_Web_Stream_Media_Subtype"
  }, {
    "DA1E6B13-8359-4050-B398-388E965BF00C", 
    "ASF_Web_Stream_Format"
  }, 
  
  // Stream Properties Object Error Correction Type GUIDs 
  {
    "20FB5700-5B55-11CF-A8FD-00805F5C442B", 
    "ASF_No_Error_Correction"
  }, {
    "BFC3CD50-618F-11CF-8BB2-00AA00B4E220", 
    "ASF_Audio_Spread"
  },
  
  // Header Extension Object GUIDs
  {
    "ABD3D211-A9BA-11cf-8EE6-00C00C205365", 
    "ASF_Reserved_1"
  }, 
    
  // Advanced Content Encryption Object System ID GUIDs
  {
    "7A079BB6-DAA4-4e12-A5CA-91D38DC11A8D", 
    "ASF_Content_Encryption_System_Windows_Media_DRM_Network_Devices"
  }, 

  // Codec List Object GUIDs
  {
    "86D15241-311D-11D0-A3A4-00A0C90348F6", 
    "ASF_Reserved_2"
  }, 
  
  // Script Command Object GUIDs
  {
    "4B1ACBE3-100B-11D0-A39B-00A0C90348F6", 
    "ASF_Reserved_3"
  }, 

  // Marker Object GUIDs
  {
    "4CFEDB20-75F6-11CF-9C0F-00A0C90349CB", 
    "ASF_Reserved_4"
  }, 

  // Mutual Exclusion Object Exclusion Type GUIDs
  {
    "D6E22A00-35DA-11D1-9034-00A0C90349BE", 
    "ASF_Mutex_Language"
  }, {
    "D6E22A01-35DA-11D1-9034-00A0C90349BE", 
    "ASF_Mutex_Bitrate"
  }, {
    "D6E22A02-35DA-11D1-9034-00A0C90349BE", 
    "ASF_Mutex_Unknown"
  }, 

  // Bandwidth Sharing Object GUIDs
  {
    "AF6060AA-5197-11D2-B6AF-00C04FD908E9", 
    "ASF_Bandwidth_Sharing_Exclusive"
  }, {
    "AF6060AB-5197-11D2-B6AF-00C04FD908E9", 
    "ASF_Bandwidth_Sharing_Partial"
  }, 

  // Standard Payload Extension System GUIDs
  {
    "399595EC-8667-4E2D-8FDB-98814CE76C1E", 
    "ASF_Payload_Extension_System_Timecode"
  }, {
    "E165EC0E-19ED-45D7-B4A7-25CBD1E28E9B", 
    "ASF_Payload_Extension_System_File_Name"
  }, {
    "D590DC20-07BC-436C-9CF7-F3BBFBF1A4DC", 
    "ASF_Payload_Extension_System_Content_Type"
  }, {
    "1B1EE554-F9EA-4BC8-821A-376B74E4C4B8", 
    "ASF_Payload_Extension_System_Pixel_Aspect_Ratio"
  }, {
    "C6BD9450-867F-4907-83A3-C77921B733AD", 
    "ASF_Payload_Extension_System_Sample_Duration"
  }, {
    "6698B84E-0AFA-4330-AEB2-1C0A98D7A44D", 
    "ASF_Payload_Extension_System_Encryption_Sample_ID"
  }

GUID

/**
 * struct { 
 *   unsigned long Data1; 
 *   unsigned short Data2; 
 *   unsigned short Data3; 
 *   unsigned char Data4[8]; 
 * } GUID;
 * 
 * see https://docs.microsoft.com/zh-tw/previous-versions/bb415594(v=msdn.10)
 * 
 * 30 26 B2 75 8E 66 CF 11  A6 D9 00 AA 00 62 CE 6C
 * Data1 -> 30 26 B2 75 -> 75B22630
 * Data2 -> 8E 66 -> 668E
 * Data3 -> CF 11 -> 11CF
 * Data4 -> A6 D9 00 AA 00 62 CE 6C -> A6D9-00AA0062CE6C
 * 75B22630-668E-11CF-A6D9-00AA0062CE6C
 */
struct guid { 
  unsigned long data1; 
  unsigned short data2; 
  unsigned short data3; 
  unsigned char data4[8]; 
};

GUID相关的几个函数

int guid(unsigned long data1, unsigned short data2, unsigned short data3, unsigned char data4[8], struct guid *out)
{
  out->data1 = data1;
  out->data2 = data2;
  out->data3 = data3;
  memcpy(out->data4, data4, 8);
  return 0;
}

// param s, guid with string format. for example: 75B22630-668E-11CF-A6D9-00AA0062CE6C
int guid_from(unsigned char s[36], struct guid *out)
{
  unsigned char data5[17];
  sscanf(s, "%lx-%hx-%hx-%s", &out->data1, &out->data2, &out->data3, data5);

  sscanf(data5, 
    "%2hhx%2hhx-%2hhx%2hhx%2hhx%2hhx%2hhx%2hhx", 
    &out->data4[0], &out->data4[1], &out->data4[2], &out->data4[3], 
    &out->data4[4], &out->data4[5], &out->data4[6], &out->data4[7]);
  return 0;
}

// param s, guid with string format. for example: 75B22630-668E-11CF-A6D9-00AA0062CE6C
int guid_to(struct guid *out, unsigned char s[36])
{
  sprintf(s, "%.8X-%.4X-%.4X-%.2hhX%.2hhX-%.2hhX%.2hhX%.2hhX%.2hhX%.2hhX%.2hhX", 
    out->data1, out->data2, out->data3, 
    out->data4[0], out->data4[1], out->data4[2], out->data4[3], 
    out->data4[4], out->data4[5], out->data4[6], out->data4[7]);
  return 0;
}

 

 

WMV

 

AVI

Codec

 

FMP4

 

 

MPG

 

MP4

 

FLV

int flv_std_read_body(FILE *fp)
{
  unsigned int pre_tag_size;

  fread(&pre_tag_size, 1, 4, fp); // PreviousTagSize0(4 bytes)
  pre_tag_size = htonl(pre_tag_size);
  printf("pre_tag_size=%u\n", pre_tag_size);

  while (! feof(fp))
  {
    struct flv_tag_header *tag_header = malloc(sizeof(struct flv_tag_header));
    struct flv_tag *tag;
    
    fread(tag_header, 1, sizeof(struct flv_tag_header), fp); // (11 bytes)

    tag = realloc(tag_header, sizeof(struct flv_tag_header) + __data_size__(tag_header));
    tag_header = (struct flv_tag_header *) tag;
    fread(tag->data, 1, __data_size__(tag_header), fp); // (data_size bytes)

    fread(&pre_tag_size, 1, 4, fp); // PreviousTagSize1, 2, ..., n(4 bytes)
    pre_tag_size = htonl(pre_tag_size);

    printf("pre_tag_size=%u, type=%u, data_size=%u, timestamp=%u, timestamp_extended=%u, stream_id=%u\n", 
      pre_tag_size, tag_header->type, __data_size__(tag_header), tag_header->timestamp, tag_header->timestamp_extended, __stream_id__(tag_header));

    switch (tag_header->type)
    {
      case AUDIO_TAG: // 8
      {
        printf("tag: audio\n");
        parse_audio(tag->data, __data_size__(tag_header));
        break;
      }
      case VIDEO_TAG: // 9
      {
        printf("tag: video\n");
        parse_video(tag->data, __data_size__(tag_header));
        break;
      }
      case SCRIPT_DATA_TAG: // 18
      {
        printf("tag: script data\n");

        parse_script_data(tag->data, __data_size__(tag_header));
        break;
      }
      default: // all others(tag) reserved.
      {
        break;
      }
    }
  }
}

int flv_std_load(FILE *fp)
{
  struct flv_header header;
  
  fread(&header, 1, sizeof(struct flv_header), fp); // (9 bytes)
  header.data_offset = htonl(header.data_offset);
  printf("signature=%.3s, version=%u, reserved0=%u, audio=%u, reserved1=%u, video=%u, data_offset=%u\n", 
    header.signature, header.version, header.reserved0, header.audio, header.reserved1, header.video, header.data_offset);
  if (header.data_offset > sizeof(struct flv_header))
  {

  }

  flv_std_read_body(fp);
  return 0;
}

 

F4V

 

音频编解码

AUDIO

frame

 * frame()
 * {
 *  header()
 *  error_check()
 *  audio_data()
 *  ancillary_data()
 * }

header

 * header()
 * {
 *    syncword	12	bits	bslbf
 *    ID	1	bit	bslbf
 *    layer	2	bits	bslbf
 *    protection_bit	1	bit	bslbf
 *    bitrate_index	4	bits	bslbf
 *    sampling_frequency	2	bits	bslbf
 *    padding_bit	1	bit	bslbf
 *    private_bit	1	bit	bslbf
 *    mode	2	bits	bslbf
 *    mode_extension	2	bits	bslbf
 *    copyright	1	bit	bslbf
 *    original/home	1	bit	bslbf
 *    emphasis	2	bits	bslbf
 * }

// layer

// 

// "11"Layer I

// "10"Layer II

// "01"Layer III

// "00"reserved

 

 * mode

 *

 * '00'stereo(also known as 立体声)

 * '01'joint_stereo(also known as 联合立体声) (intensity_stereo al-

 *        so known as 强度立体声 and/or ms_stereo) 

 *        In Layer I and II the joint_stereo mode is intensity_stereo, 

 *        in Layer III it is intensity_stereo and/or ms_stereo. 

 *

 * '10'dual_channel (also known as 双通道)

 * '11'single_channel (also known as 单通道)

 

error_check

 * error_check()
 * {
 *  if  (protection_bit==0)
 *   crc_check 	 16	bits	rpchof
 * }

audio_data

- Audio data, Layer I

 * audio_data()
 * {
 *  if (mode==single_channel)
 *  {
 *   for (sb=0; sb<32; sb++) 
 *    allocation[sb]	4	bits	uimsbf
 *   for (sb=0; sb<32; sb++) 
 *    if (allocation[sb]!=0)
 *     scalefactor[sb]	6	bits	uimsbf
 *   for (s=0; s<12; s++)
 *    for (sb=0; sb<32; sb++) 
 *     if (allocation[sb]!=0)
 *      sample[sb][s]	2..15	bits	uimsbf
 *  }
 *  if (mode==stereo) || (mode==dual_channel)
 *  {
 *   for (sb=0; sb<32; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     allocation[ch][sb]	4	bits	bsmsbf
 *   for (sb=0; sb<32; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[ch][sb]!=0)
 *      scalefactor[ch][sb]	6	bits	uimsbf
 *   for (s=0; s<12; s++)
 *    for (sb=0; sb<32; sb++)
 *     for (ch=0; ch<2; ch++) 
 *      if (allocation[ch][sb]!=0)
 *       sample[ch][sb][s]	2..15	bits	uimsbf
 *  }
 *  if (mode==intensity_stereo) 
 *  {
 *   for (sb=0; sb<bound; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     allocation[ch][sb]	4	bits	uimsbf
 *   for (sb=bound; sb<32; sb++) 
 *    allocation[sb]	4	bits	uimsbf
 *   for (sb=0; sb<bound; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[ch][sb]!=0)
 *      scalefactor[ch][sb]	6	bits	uimsbf
 *   for (sb=bound; sb<32; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[sb]!=0)
 *      scalefactor[ch][sb]	6	bits	uimsbf
 *   for (s=0; s<12; s++)
 *   {
 *    for (sb=0; sb<bound; sb++)
 *     for (ch=0; ch<2; ch++) 
 *      if (allocation[ch][sb]!=0)
 *       sample[ch][sb][s]	2..15	bits	uimsbf
 *    for (sb=bound; sb<32; sb++)
 *     if (allocation[sb]!=0)
 *      sample[sb][s]	2..15	bits	uimsbf
 *   }
 *  }
 * }

- Audio data, Layer II

 * audio_data()
 * {
 *  if (mode==single_channel)
 *  {
 *   for (sb=0; sb<sblimit; sb++) 
 *    allocation[sb]	2..4	bits	uimsbf
 *   for (sb=0; sb<sblimit; sb++) 
 *    if (allocation[sb]!=0)
 *     scfsi[sb]	2	bits	bslbf
 *   for (sb=0; sb<sblimit; sb++) 
 *    if (allocation[sb]!=0)
 *    {
 *     if (scfsi[sb]==0) 
 *     { 
 *      scalefactor[sb][0] 	6	bits	uimsbf
 *      scalefactor[sb][1] 	6	bits	uimsbf
 *      scalefactor[sb][2] }	6	bits	uimsbf
 *     if (scfsi[sb]==1) || (scfsi[sb]==3)
 *     { 
 *      scalefactor[sb][0] 	6	bits	uimsbf
 *      scalefactor[sb][2] }	6	bits	uimsbf
 *     if (scfsi[sb]==2)
 *      scalefactor[sb][0]	6	bits	uimsbf
 *    }
 *   for (gr=0; gr<12; gr++)
 *    for (sb=0; sb<sblimit; sb++) 
 *     if (allocation[sb]!=0)
 *     {
 *      if (grouping[sb])
 *       samplecode[sb][gr]	5..10	bits	uimsbf
 *      else 
 *       for (s=0; s<3; s++)
 *        sample[sb][3*gr+s]	2..16	bits	uimsbf 
 *     }
 *  }
 *
 *  if (mode==stereo) || (mode==dual_channel)
 *  {
 *   for (sb=0; sb<sblimit; sb++)
 *    for (ch=0; ch<2; ch++)
 *     allocation[ch][sb]	2..4	bits	uimsbf
 *   for (sb=0; sb<sblimit; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[ch][sb]!=0)
 *      scfsi[ch][sb]	2	bits	bslbf
 *   for (sb=0; sb<sblimit; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[ch][sb]!=0)
 *     {
 *      if (scfsi[ch][sb]==0) 
 *      { 
 *       scalefactor[ch][sb][0] 	6	bits	uimsbf
 *       scalefactor[ch][sb][1] 	6	bits	uimsbf
 *       scalefactor[ch][sb][2] }	6	bits	uimsbf 
 *      if (scfsi[ch][sb]==1) || (scfsi[ch][sb]==3)
 *      { 
 *       scalefactor[ch][sb][0] 	6	bits	uimsbf
 *       scalefactor[ch][sb][2] }	6	bits	uimsbf
 *      if (scfsi[ch][sb]==2)
 *       scalefactor[ch][sb][0]	6	bits	uimsbf
 *     }
 *   for (gr=0; gr<12; gr++)
 *    for (sb=0; sb<sblimit; sb++) 
 *     for (ch=0; ch<2; ch++)
 *      if (allocation[ch][sb]!=0)
 *      {
 *       if (grouping[ch][sb])
 *        samplecode[ch][sb][gr]	5..10	bits	uimsbf
 *       else for (s=0; s<3; s++)
 *        sample[ch][sb][3*gr+s]	2..16	bits	uimsbf
 *      }
 *  }
 *
 *  if (mode==intensity_stereo) 
 *  {
 *   for (sb=0; sb<bound; sb++)
 *    for (ch=0; ch<2; ch++)
 *     allocation[ch][sb]	2..4	bits	uimsbf
 *   for (sb=bound; sb<sblimit; sb++)
 *    allocation[sb]	2..4	bits	uimsbf
 *   for (sb=0; sb<bound; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[ch][sb]!=0)
 *      scfsi[ch][sb]	2	bits	bslbf
 *   for (sb=bound; sb<sblimit; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[sb]!=0)
 *      scfsi[ch][sb]	2	bits	bslbf
 *   for (sb=0; sb<bound; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[ch][sb]!=0)
 *     {
 *      if (scfsi[ch][sb]==0) 
 *      { 
 *       scalefactor[ch][sb][0] 	6	bits	uimsbf
 *       scalefactor[ch][sb][1] 	6	bits	uimsbf
 *       scalefactor[ch][sb][2] }	6	bits	uimsbf
 *      if (scfsi[ch][sb]==1) || (scfsi[ch][sb]==3)
 *      { 
 *       scalefactor[ch][sb][0] 	6	bits	uimsbf
 *       scalefactor[ch][sb][2] }	6	bits	uimsbf
 *      if (scfsi[ch][sb]==2)
 *       scalefactor[ch][sb][0]	6	bits	uimsbf
 *     }
 *   for (sb=bound; sb<sblimit; sb++) 
 *    for (ch=0; ch<2; ch++)
 *     if (allocation[sb]!=0)
 *     {
 *      if (scfsi[ch][sb]==0) 
 *      { 
 *       scalefactor[ch][sb][0] 	6	bits	uimsbf
 *       scalefactor[ch][sb][1] 	6	bits	uimsbf
 *       scalefactor[ch][sb][2] }	6	bits	uimsbf
 *      if (scfsi[ch][sb]==1) || (scfsi[ch][sb]==3)
 *      { 
 *       scalefactor[ch][sb][0] 	6	bits	uimsbf
 *       scalefactor[ch][sb][2] }	6	bits	uimsbf
 *      if (scfsi[ch][sb]==2)
 *       scalefactor[ch][sb][0]	6	bits	uimsbf
 *     }
 *   for (gr=0; gr<12; gr++)
 *   {
 *    for (sb=0; sb<bound; sb++) 
 *     for (ch=0; ch<2; ch++)
 *      if (allocation[ch][sb]!=0)
 *      {
 *       if (grouping[ch][sb])
 *        samplecode[ch][sb][gr]	5..10	bits	uimsbf
 *       else for (s=0; s<3; s++)
 *        sample[ch][sb][3*gr+s]	2..16	bits	uimsbf
 *      }
 *    for (sb=bound; sb<sblimit; sb++) 
 *     if (allocation[sb]!=0)
 *     {
 *      if (grouping[sb])
 *       samplecode[sb][gr]	5..10	bits	uimsbf
 *      else for (s=0; s<3; s++)
 *       sample[sb][3*gr+s]	2..16	bits	uimsbf 
 *     }
 *   }
 *  }
 * }

- Audio data, Layer III

 * audio_data()
 * {
 *  if (mode == single_channel)
 *  {
 *   main_data_end	9	bits	uimsbf
 *   private_bits	5	bits	bslbf
 *   for (scfsi_band=0; scfsi_band<4; scfsi_band++)
 *    scfsi[scfsi_band]	1	bits	bslbf
 *   for (gr=0; gr<2; gr++) 
 *   {
 *    part2_3_length[gr]	12	bits	uimsbf
 *    big_values[gr]	9	bits	uimsbf
 *    global_gain[gr]	8	bits	uimsbf
 *    scalefac_compress[gr]	4	bits	bslbf
 *    blocksplit_flag[gr]	1	bit	bslbf
 *    if (blocksplit_flag[gr])
 *    {
 *     block_type[gr]	2	bits	bslbf
 *     switch_point[gr]	1	bits	uimsbf
 *     for (region=0; region<2; region++)
 *      table_select[region][gr]	5	bits	bslbf
 *     for (window=0; window<3; window++)
 *      subblock_gain[window][gr]	3	bits	uimsbf
 *    }
 *    else
 *    {
 *     for (region=0; region<3; region++)
 *      table_select[region][gr]	5	bits	bslbf
 *     region_address1[gr]	4	bits	bslbf
 *     region_address2[gr]	3	bits	bslbf
 *    }
 *    preflag[gr]	1	bit	bslbf
 *    scalefac_scale[gr]	1	bit	bslbf
 *    count1table_select[gr]	1	bit	bslbf
 *   }
 * 
 *   // 
 *   // The main_data follows.  It does not follow the above side information 
 *   // in the bitstream.  The main_data ends at a location in the main_data 
 *   // bitstream preceding the frame header of the following frame at an offset 
 *   // given by the value of main_data_end (see definition of main_data_end 
 *   // and 3-Annex Fig.3-A.7.1)
 *   // 
 *   for (gr=0; gr<2; gr++)
 *    if (blocksplit_flag[gr] == 1 && block_type[gr] == 2)
 *    {
 *     for (cb=0; cb<switch_point_l[gr]; cb++)
 *      if (scfsi[cb]==0) || (gr==0) 
 *       scalefac[cb][gr]	0..4	bits	uimsbf
 *     for (cb=switch_point_s[gr]; cb<cblimit_short; cb++)
 *      for (window=0; window<3; window++)
 *       if (scfsi[cb]==0) || (gr==0) 
 *        scalefac[cb][window][gr]	0..4	bits	uimsbf
 *    }
 *    else
 *     for (cb=0; cb<cblimit; cb++)
 *      if (scfsi[cb]==0) || (gr==0)
 *       scalefac[cb][gr]	0..4	bits	uimsbf
 *   Huffmancodebits  	    (part2_3_length-part2_length)	bits	bslbf
 *   while (position != main_data_end)
 *   {
 *    ancillary_bit	1	bit	bslbf
 *   }
 *
 *  }
 * 
 *  if (mode==stereo) || (mode==dual_channel) || (mode==ms_stereo)
 *  {
 *   main_data_end		9 bits	uimsbf
 *   private_bits		3 bits	bslbf
 *   for (ch=0; ch<2; ch++)
 *    for (scfsi_band=0; scfsi_band<4; scfsi_band++)
 *     scfsi[scfsi_band][ch]		1 bits	bslbf
 *   for (gr=0; gr<2; gr++)
 *    for (ch=0; ch<2; ch++}
 *     part2_3_length[gr][ch]	12	bits	uimsbf
 *   big_values[gr][ch]	9	bits	uimsbf
 *   global_gain[gr][ch]	8	bits	uimsbf
 *   scalefac_compress[gr][ch]	4	bits	bslbf
 *   blocksplit_flag[gr][ch]	1	bit	bslbf
 *   if (blocksplit_flag[gr][ch])
 *   {
 *    block_type[gr][ch]	2	bits	bslbf
 *    switch_point[gr][ch]	1	bits	uimsbf
 *    for (region=0; region<2; region++)
 *     table_select[region][gr][ch]	5	bits	bslbf
 *    for (window=0; window<3; window++)
 *     subblock_gain[window][gr][ch]	3	bits	uimsbf
 *   }
 *   else
 *   {
 *    for (region=0; region<3; region++)
 *     table_select[region][gr][ch]	5	bits	bslbf
 *    region_address1[gr][ch]	4	bits	bslbf
 *    region_address2[gr][ch]	3	bits	bslbf
 *   }
 *   preflag[gr][ch]	1	bit	bslbf
 *   scalefac_scale[gr][ch]	1	bit	bslbf
 *   count1table_select[gr][ch]	1	bit	bslbf
 *
 *   // 
 *   // The main_data follows. It does not follow the above side information 
 *   // in the bitstream. The main_data ends at a location in the main_data 
 *   // bitstream preceding the frame header of the following frame at an offset 
 *   // given by the value of main_data_end.
 *   // 
 *   for (gr=0; gr<2; gr++)
 *    for (ch=0; ch<2; ch++) {
 *     if (blocksplit_flag[gr][ch] == 1 && block_type[gr][ch] == 2)
 *     {
 *      for (cb=0; cb<switch_point_l[gr][ch]; cb++)
 *       if (scfsi[cb]==0) || (gr==0) 
 *        scalefac[cb][gr][ch]	0..4	bits	uimsbf
 *      for (cb=switch_point_s[gr][ch]; cb<cblimit_short; cb++)
 *       for (window=0; window<3; window++)
 *        if (scfsi[cb]==0) || (gr==0) 
 *         scalefac[cb][window][gr][ch]	0..4	bits	uimsbf
 *     }
 *     else
 *      for (cb=0; cb<cblimit; cb++)
 *       if (scfsi[cb]==0) || (gr==0) 
 *        scalefac[cb][gr][ch]	0..4	bits	uimsbf
 *     Huffmancodebits 	(part2_3_length-part2_length)	bits	bslbf
 *     while (position != main_data_end)
 *     {
 *      ancillary_bit	1	bit	bslbf
 *     }
 *
 *    }
 *  }
 * }

 

 

MP3

 

MPEG Audio Layer3

 

视频编解码

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