Changes between Version 30 and Version 31 of SV8Specification
- Timestamp:
- 02/15/07 12:32:13 (17 years ago)
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SV8Specification
v30 v31 26 26 All unused bits in a packet MUST be null.[[BR]] 27 27 28 || '''Field''' || '''Size (bits)''' || ''' Payload''' ||28 || '''Field''' || '''Size (bits)''' || '''Value''' || 29 29 || Key || 16 || "EX" || 30 30 || Size || n*8; 0 < n < 10 || 0x1A || … … 34 34 == Summary of reserved packet keys == 35 35 36 Allowed chars in key are [A-Z] (65 <= value <= 90), so 676 keys are valid out of 65536 possible. 37 36 38 || '''Packet Name''' || '''Key''' || '''Mandatory''' || 37 39 || Stream Header || SH || yes || 38 40 || Replaygain || RG || yes || 39 41 || Encoder Info || EI || no || 40 || Edition || ED || no ||41 42 || Seek Table Offset || SO || no || 42 43 || Audio Packet || AP || yes || … … 46 47 == Stream Header Packet == 47 48 48 This packet key is "S I".[[BR]]49 This packet key is "SH".[[BR]] 49 50 It contains the informations needed to decode the stream. This block is mandatory and must be written before the first audio packet.[[BR]] 50 51 51 || '''Field''' || '''Size (bits)''' || ''' Payload''' || '''Comment''' ||52 || '''Field''' || '''Size (bits)''' || '''Value''' || '''Comment''' || 52 53 || CRC || 32 || || CRC 32 of the block (this field excluded). 0 = invalid || 53 54 || Stream version || 8 || 8 || Bitstream version || 54 55 || Sample count || n*8; 0 < n < 10 || || Number of samples in the stream. 0 = unknown || 56 || Beginning silence || n*8; 0 < n < 10 || || Number of samples to skip at the beginning of the stream || 57 || End silence || n*8; 0 < n < 10 || || Number of samples to skip at the end of the stream || 55 58 || Sample frequency || 3 || 0..7 || See table below || 56 59 || Channel count || 4 || 1..16 || Number of channels in the stream || 57 60 || Max used bands || 5 || 1..32 || Maximum number of bands used in the file || 58 61 || MS used || 1 || || True if Mid Side Stereo is enabled || 59 || Audio block frames || 3 || 0..7 || Number of frames per audio packet (4^value =(1..16384)) ||62 || Audio block frames || 3 || 0..7 || Number of frames per audio packet (4^value^=(1..16384)) || 60 63 61 64 Do we need to specify the channel position ? Is there standard positions / order of the channels ? 65 66 The SV8 stream allow only to start decoding on first packet frame, so cutting the stream require to cut on packet boundaries. Beginning / End silence fields provides more precise cutting possibilities.[[BR]] 62 67 63 68 Frequency table … … 75 80 It contains the necessary data needed to apply replaygain on the current stream. This packet is mandatory and must be written before the first audio packet.[[BR]] 76 81 77 || '''Field''' || '''Size (bits)''' || ''' Payload''' || '''Comment''' ||78 || ReplayGain version || 8 || || The replay gain version - must be aligned on a byte -||82 || '''Field''' || '''Size (bits)''' || '''Value''' || '''Comment''' || 83 || ReplayGain version || 8 || 1 || The replay gain version || 79 84 || Title gain || 16 || || The loudness calculated for the title, ''and not the gain that the player must apply'' || 80 85 || Title peak || 16 || || || … … 82 87 || Album peak || 16 || || || 83 88 84 The replay gain values are stored in dB in Q8.8 format (maybe Q7.9 or relative to the max value for the bitdepth is better ?).[[BR]] 89 The replay gain values are stored in dB in Q8.8 format.[[BR]] 90 The 0 value means that this field has not been computed (no gain must be applied in this case.[[BR]] 91 exemples :[[BR]] 92 * Replay gain finds that this title as a loudness of 78.56 dB, it will be encoded as 78.56 * 256 ~ 20111 = 0x4E8F 93 * For 16 bits output (range [-32767 32768]), the max is 68813 (out of range). it will be encoded as 20 * log10(68813) * 256 ~ 24769 = 0x60C1 94 * For float output (range [-1 1]), the max is 0.96. it will be encoded as 20 * log10(0.96 * 2^15^) * 256 ~ 23029 = 0x59F5 (for peak values it is suggested to round to nearest higher integer) 85 95 86 96 == Encoder Info Packet == … … 88 98 This packet key is "EI".[[BR]] 89 99 90 || '''Field''' || '''Size (bits)''' || ''' Payload''' || '''Comment''' ||100 || '''Field''' || '''Size (bits)''' || '''Value''' || '''Comment''' || 91 101 || Profile || 7 || 0..15.875 || quality in 4.3 format || 92 102 || PNS tool || 1 || True if enabled || || … … 96 106 97 107 98 == Edition Packet ==99 100 This packet key is "ED"[[BR]]101 The SV8 stream allow only to start decoding on first packet frame, so cutting the stream require to cut on packet boundaries. This packet102 provides more precise cutting possibilities.[[BR]]103 This packet must be written before the first audio packet.104 105 || '''Field''' || '''Size (bits)''' || '''Payload''' || '''Comment''' ||106 || Beginning silence || n*8; 0 < n < 10 || || Number of samples to skip at the beginning of the stream ||107 || End silence || n*8; 0 < n < 10 || || Number of samples to skip at the end of the stream ||108 109 110 108 == Seek Table Offset Packet == 111 109 112 110 This packet key is "SO".[[BR]] 113 It contains an offset to the seek table packet. 111 It contains an offset to the seek table packet.[[BR]] 112 This packet must be written before the first audio packet. This packet must be present if the "ST" packet is present and is written after the first audio packet. 114 113 115 || '''Field''' || '''Size (bits)''' || ''' Payload''' || '''Comment''' ||114 || '''Field''' || '''Size (bits)''' || '''Value''' || '''Comment''' || 116 115 || Offset || n*8; 0 < n < 10 || || Offset from this packet to the seek table packet || 117 116 … … 122 121 It contains audio frames. The first frame is a key frame.[[BR]] 123 122 124 || '''Field''' || '''Size (bits)''' || ''' Payload''' || '''Comment''' ||125 || Audio Frames || ? || ||n (or less if last packet) frames of audio as defined in SH packet ||123 || '''Field''' || '''Size (bits)''' || '''Comment''' || 124 || Audio Frames || ? || n (or less if last packet) frames of audio as defined in SH packet || 126 125 127 126 … … 130 129 This packet key is "ST".[[BR]] 131 130 132 || '''Field''' || '''Size (bits)''' || ''' Payload''' || '''Comment''' ||131 || '''Field''' || '''Size (bits)''' || '''Value''' || '''Comment''' || 133 132 || Seek Count || n*8; 0 < n < 10 || || Number of seek elements in this table || 134 133 || Seek Distance || 4 || 0..15 || Distance between referenced blocks = 2^Value^ || … … 137 136 Format of seek data :[[BR]] 138 137 139 - Reference offset for seeking is the musepack magic number[[BR]] 140 - First 2 values are stored using the same code as the packet size code.[[BR]] 141 - Next values are coded as :[[BR]] 138 * Reference offset for seeking is the musepack magic number 139 * First 2 values are stored using the same code as the packet size code. 140 * Next values are coded as : 142 141 {{{ 143 142 code = value(n) - 2*value(n-1) + value(n-2)
