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mirror of https://github.com/wader/fq.git synced 2024-12-25 22:34:14 +03:00
fq/format/mpeg/adts_frame.go
Mattias Wadman 1ddea1ada3 interp,format: Refactor registry usage and use function helpers
Move registry to interp and add support for functions and filesystems.
This will be used later for allow formats to add own functions and fq code.

Add gojqextra function helpers to have more comfortable API to add functions.
Takes care of argument type casting and JQValue:s and some more things.

Refactor interp package to use new function helper and registry. Probably
fixes a bunch of JQValue bugs and other type errors.

Refactor out some mpeg nal things to mpeg format.

Refactor interp jq code into display.q and init.jq.

Remove undocumented aes_ctr funciton, was a test. Hopefully will add more crypto things laster.
2022-07-16 19:24:13 +02:00

106 lines
3.7 KiB
Go

package mpeg
// https://github.com/mstorsjo/fdk-aac/blob/f285813ec15e7c6f8e4839c9eb4f6b0cd2da1990/libMpegTPEnc/src/tpenc_asc.cpp
// https://www.iis.fraunhofer.de/content/dam/iis/de/doc/ame/wp/FraunhoferIIS_Application-Bulletin_AAC-Transport-Formats.pdf
// https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/aac_adtstoasc_bsf.c
import (
"github.com/wader/fq/format"
"github.com/wader/fq/pkg/decode"
"github.com/wader/fq/pkg/interp"
"github.com/wader/fq/pkg/scalar"
)
var aacFrameFormat decode.Group
func init() {
interp.RegisterFormat(decode.Format{
Name: format.ADTS_FRAME,
Description: "Audio Data Transport Stream frame",
DecodeFn: adtsFrameDecoder,
Dependencies: []decode.Dependency{
{Names: []string{format.AAC_FRAME}, Group: &aacFrameFormat},
},
})
}
var protectionAbsentNames = scalar.BoolToDescription{
true: "No CRC",
false: "Has CRC",
}
func adtsFrameDecoder(d *decode.D, in any) any {
/*
adts_frame() {
adts_fixed_header();
adts_variable_header();
if (number_of_raw_data_blocks_in_frame == 0) {
adts_error_check();
raw_data_block();
} else {
adts_header_error_check();
for( i = 0; i <= number_of_raw_data_blocks_in_frame; i++ ) {
raw_data_block();
adts_raw_data_block_error_check();
}
}
}
*/
// A 12 syncword 0xFFF, all bits must be 1
// B 1 MPEG Version: 0 for MPEG-4, 1 for MPEG-2
// C 2 Layer: always 0
// D 1 protection absent, Warning, set to 1 if there is no CRC and 0 if there is CRC
// E 2 profile, the MPEG-4 Audio Object Type minus 1
// F 4 MPEG-4 Sampling Frequency Index (15 is forbidden)
// G 1 private bit, guaranteed never to be used by MPEG, set to 0 when encoding, ignore when decoding
// H 3 MPEG-4 Channel Configuration (in the case of 0, the channel configuration is sent via an inband PCE)
// I 1 originality, set to 0 when encoding, ignore when decoding
// J 1 home, set to 0 when encoding, ignore when decoding
// K 1 copyrighted id bit, the next bit of a centrally registered copyright identifier, set to 0 when encoding, ignore when decoding
// L 1 copyright id start, signals that this frame's copyright id bit is the first bit of the copyright id, set to 0 when encoding, ignore when decoding
// M 13 frame length, this value must include 7 or 9 bytes of header length: FrameLength = (ProtectionAbsent == 1 ? 7 : 9) + size(AACFrame)
// O 11 Buffer fullness
// P 2 Number of AAC frames (RDBs) in ADTS frame minus 1, for maximum compatibility always use 1 AAC frame per ADTS frame
// Q 16 CRC if protection absent is 0
d.FieldU12("syncword", d.AssertU(0b1111_1111_1111), scalar.ActualBin)
d.FieldU1("mpeg_version", scalar.UToSymStr{0: "mpeg4", 1: "mpeg2_aac"})
d.FieldU2("layer", d.AssertU(0))
protectionAbsent := d.FieldBool("protection_absent", protectionAbsentNames)
objectType := d.FieldU2("profile", scalar.ActualUAdd(1), format.MPEGAudioObjectTypeNames)
d.FieldUFn("sampling_frequency", decodeEscapeValueAbsFn(4, 24, 0), frequencyIndexHzMap)
d.FieldU1("private_bit")
d.FieldU3("channel_configuration", channelConfigurationNames)
d.FieldU1("originality")
d.FieldU1("home")
d.FieldU1("copyrighted")
d.FieldU1("copyright")
frameLength := d.FieldU13("frame_length")
dataLength := int64(frameLength - 7)
if !protectionAbsent {
// TODO: multuple RDBs CRCs
dataLength -= 2
}
d.FieldU11("buffer_fullness")
numberOfRDBs := d.FieldU2("number_of_rdbs", scalar.ActualUAdd(1))
if !protectionAbsent {
d.FieldU16("crc")
}
if dataLength < 0 {
d.Fatalf("dataLength < 0")
}
d.FieldArray("raw_data_blocks", func(d *decode.D) {
for i := uint64(0); i < numberOfRDBs; i++ {
d.FieldFormatLen("raw_data_block", dataLength*8, aacFrameFormat, format.AACFrameIn{ObjectType: int(objectType)})
}
})
return nil
}