fq/format/flv/flv.go

//go:build ignore

package flv

// TODO: make it useful
// https://rtmp.veriskope.com/pdf/video_file_format_spec_v10.pdf

import (
	"github.com/wader/fq/format"
	"github.com/wader/fq/format/registry"
	"github.com/wader/fq/pkg/decode"
	"github.com/wader/fq/pkg/scalar"
)

func init() {
	registry.MustRegister(decode.Format{
		Name:        format.FLV,
		Description: "Flash video",
		Groups:      []string{format.PROBE},
		DecodeFn:    flvDecode,
	})
}

const (
	audioData        = 8
	videoData        = 9
	scriptDataObject = 18
)

var tagTypeNames = scalar.UToSymStr{
	audioData:        "audioData",
	videoData:        "videoData",
	scriptDataObject: "scriptDataObject",
}

const (
	typeNumber      = 0
	typeBoolean     = 1
	typeString      = 2
	typeObject      = 3
	typeMovieClip   = 4
	typeNull        = 5
	typeUndefined   = 6
	typeReference   = 7
	typeECMAArray   = 8
	typeObjectEnd   = 9
	typeStrictArray = 10
	typeDate        = 11
	typeLongString  = 12
)

var typeNames = scalar.UToSymStr{
	typeNumber:      "Number",
	typeBoolean:     "Boolean",
	typeString:      "String",
	typeObject:      "Object",
	typeMovieClip:   "MovieClip",
	typeNull:        "Null",
	typeUndefined:   "Undefined",
	typeReference:   "Reference",
	typeECMAArray:   "ECMAArray",
	typeObjectEnd:   "ObjectEnd",
	typeStrictArray: "StrictArray",
	typeDate:        "Date",
	typeLongString:  "LongString",
}

func flvDecode(d *decode.D, in any) any {
	var fieldScriptDataObject func()
	var fieldScriptDataVariable func(d *decode.D, name string)

	fieldScriptDataString := func(d *decode.D, name string) {
		d.FieldStrFn(name, func(d *decode.D) string {
			l := d.U16()
			return d.UTF8(int(l))
		})
	}
	fieldScriptDataStringLong := func(d *decode.D, name string) {
		d.FieldStrFn(name, func(d *decode.D) string {
			l := d.U32()
			return d.UTF8(int(l))
		})
	}

	fieldScriptDataVariable = func(d *decode.D, name string) {
		d.FieldStruct(name, func(d *decode.D) {
			fieldScriptDataString(d, "name")
			fieldScriptDataString(d, "data")
		})
	}

	fieldScriptDataValue := func(d *decode.D, _ string) uint64 {
		typ := d.FieldU8("type", typeNames)
		if typ == typeECMAArray {
			d.FieldU32("ecma_array_length")
		}

		switch typ {
		case typeNumber:
			d.FieldF64("number")
		case typeBoolean:
			d.FieldU8("boolean")
		case typeString:
			fieldScriptDataString(d, "string")
		case typeObject:
			fieldScriptDataObject()
		case typeMovieClip:
			fieldScriptDataString(d, "path")
		case typeNull:
		case typeUndefined:
		case typeReference:
			d.FieldU16("reference")
		case typeECMAArray:
			d.FieldArray("array", func(d *decode.D) {
				for {
					if d.PeekBits(24) == typeObjectEnd { // variableEnd?
						d.FieldU24("end")
						break
					}
					fieldScriptDataVariable(d, "sasdadas")
				}
			})
		case typeStrictArray:
			length := d.FieldU32("length")
			for i := uint64(0); i < length; i++ {
				fieldScriptDataVariable(d, "sasdadas")
			}
		case typeDate:
			d.FieldF64("date_time")
			d.FieldS16("local_data_time_offset")

		case typeLongString:
			fieldScriptDataStringLong(d, "asdsad")

		case typeObjectEnd: // variableEnd also?

		}

		return typ
	}

	fieldScriptDataObject = func() {
		d.FieldStruct("object", func(d *decode.D) {
			fieldScriptDataString(d, "name")
			fieldScriptDataValue(d, "data")
		})
	}

	d.FieldUTF8("signature", 3, d.AssertStr("FLV"))
	d.FieldU8("version")
	d.FieldU5("type_flags_reserved", d.AssertU(0))
	d.FieldU1("type_flags_audio")
	d.FieldU1("type_flags_reserved", d.AssertU(0))
	d.FieldU1("type_flags_video")
	dataOffset := d.FieldU32("data_offset")

	d.SeekAbs(int64(dataOffset) * 8)

	d.FieldArray("tags", func(d *decode.D) {
		for !d.End() {
			d.FieldStruct("tag", func(d *decode.D) {
				d.FieldU32("previous_tag_size")
				tagType := d.FieldU8("tag_type", tagTypeNames)
				dataSize := d.FieldU24("data_size")
				d.FieldU24("timestamp")
				d.FieldU8("timestamp_extended")
				d.FieldU24("stream_id")

				switch tagType {
				case audioData, videoData:
					d.SeekRel(int64(dataSize) * 8)
				case scriptDataObject:
					for {
						if d.PeekBits(24) == typeObjectEnd {
							d.FieldU24("end")
							break
						}
						fieldScriptDataObject()
					}
				}
			})
		}
	})

	return nil
}