@mediafish/flv

flv

A library to read/write Flash Video file format (only supports AAC/AVC)

Install

Usage

Example of reading FLV file

const {readFile, print} = require('@mediafish/flv');

const buf = fs.readFileSync('test.flv');
const [offset, flv] = readFile(buf, offset);
print(flv);
/*
FLVFile {
  FLVHeader: {
    version: 1,
    hasAudio: true,
    hasVideo: true
  },
  body: [
    FLVTag: {
      timestamp: 0,
      AVC: {
        frameType: 'keyframe',
        codec: 'AVC',
        packetType: 'NALU',
        data: <Buffer length=1024 >
      }
    },
    FLVTag: {
      timestamp: 0,
      AAC: {
        format: 'AAC',
        sampleRate: '44kHz',
        size: '16Bit',
        isStereo: true,
        packetType: 'raw',
        data: <Buffer length=1024 >
      }
    },
    ...
  ]
}
*/

Example of reading Video and Audio

const {readVideo, readAudio, print} = require('@mediafish/flv');

const [offset, video] = readVideo(buf1, offset);
print(video);
/*
AVC: {
  frameType: 'keyframe',
  codec: 'AVC',
  packetType: 'NALU',
  data: <Buffer length=1024 >
}
*/

const [offset, audio] = readAudio(buf2, offset);
print(audio);
/*
AAC: {
  format: 'AAC',
  sampleRate: '44kHz',
  size: '16Bit',
  isStereo: true,
  packetType: 'raw',
  data: <Buffer length=1024 >
}
*/

Example of writing FLV

const {writeData, type: {Video, AVC, Audio, AAC, FLVFile, FLVHeader, FLVTag}} = require('@mediafish/flv');

const video = new AVC({
  frameType: Video.FrameType.keyframe,
  codec: Video.Codec.AVC,
  packetType: AVC.PacketType.NALU,
  compositionTimeOffset: 0,
  data: buf1
});


const audio = new AAC({
  format: Audio.SoundFormat.AAC,
  sampleRate: Audio.SampleRate._44kHz,
  size: Audio.SampleLength._16Bit,
  isStereo: true,
  packetType: AAC.PacketType.Raw,
  data: buf2
});

const header = new FLVHeader({version: 1, hasAudio: true, hasVideo: true});

const tags = [
  new FLVTag({type: FLVTag.TagType.audio, timestamp: 0, data: audio}),
  new FLVTag({type: FLVTag.TagType.video, timestamp: 0, data: video})
];

const flv = new FLVFile(header, tags);

// First, pass null instead of a buffer to detect how many bytes are needed
const byteLength = writeData(flv, null, 0);
// And then alloc a buff
const buffer = Buffer.alloc(byteLength);
// Finally, write the data actually to the buffer
writeData(flv, buffer, 0);

Example of writing Video and Audio

const {writeData, type: {Video, AVC, Audio, AAC}} = require('@mediafish/flv');

const video = new AVC({
  frameType: Video.FrameType.keyframe,
  codec: Video.Codec.AVC,
  packetType: AVC.PacketType.NALU,
  compositionTimeOffset: 0,
  data: buf1
});


const audio = new AAC({
  format: Audio.SoundFormat.AAC,
  sampleRate: Audio.SampleRate._44kHz,
  size: Audio.SampleLength._16Bit,
  isStereo: true,
  packetType: AAC.PacketType.Raw,
  data: buf2
});

// First, pass null instead of a buffer to detect how many bytes are needed
const videoLength = writeData(video, null, 0);
const audioLength = writeData(audio, null, 0);
// And then alloc a buff
const buffer = Buffer.alloc(videoLength + audioLength);
// Finally, write the data actually to the buffer
let offset = 0;
offset = writeData(video, buffer, offset);
offset = writeData(audio, buffer, offset);

API

readFile(buffer, offset)

Read FLV file from the buffer

params

Name	Type	Required	Default	Description
buffer	Buffer or Uint8Array	Yes	N/A	The buffer from which the data is read
offset	number	Yes	N/A	An integer to specify the position within the buffer

return value

An array containing the following pair of values

Index	Type	Description
[0]	number	An integer to indicate the position from which the next data should be read
[1]	FLVFile	The read data (See Data format)

readVideo(buffer, offset, length)

Read video data from the buffer

params

Name	Type	Required	Default	Description
buffer	Buffer or Uint8Array	Yes	N/A	The buffer from which the data is read
offset	number	Yes	N/A	An integer to specify the position within the buffer
length	number	Yes	N/A	An integer to specify how many bytes to read

return value

An array containing the following pair of values

Index	Type	Description
[0]	number	An integer to indicate the position from which the next data should be read
[1]	AVC	The read data (See Data format)

readAudio(buffer, offset)

Read audio data from the buffer

params

Name	Type	Required	Default	Description
buffer	Buffer or Uint8Array	Yes	N/A	The buffer from which the data is read
offset	number	Yes	N/A	An integer to specify the position within the buffer
length	number	Yes	N/A	An integer to specify how many bytes to read

return value

An array containing the following pair of values

Index	Type	Description
[0]	number	An integer to indicate the position from which the next data should be read
[1]	AAC	The read data (See Data format)

writeData(data, buffer, offset)

Write data to the buffer

params

Name	Type	Required	Default	Description
data	AVC/AAC/FLVHeader/FLVTag/FLVFile	Yes	N/A	The data to be written to the buffer
buffer	Buffer	No	null	The buffer to which the data is written. If null, only the necessary buffer size is calculated
offset	number	Yes	N/A	An integer to specify the position within the buffer

return value

An integer to indicate the position from which the next data should be read

setOptions(obj)

Updates the option values

params

Name	Type	Required	Default	Description
obj	Object	Yes	{}	An object holding option values which will be used to overwrite the internal option values.

supported options

Name	Type	Default	Description
strictMode	boolean	false	If true, the function throws an error when the method invocations failed. If false, the function just logs the error and continues to run.

getOptions()

Retrieves the current option values

return value

A cloned object containing the current option values

Data format

This section describes the structure of the data that can be read / written using readFile/readAudio/readVideo

FLVFile

Property	Type	Description
header	FLVHeader	An instance of FLVHeader
body	[FLVTag]	An array of FLVTag

FLVHeader

Property	Type	Description
version	number	FLV version
hasAudio	boolean	Audio tags are present
hasVideo	boolean	Video tags are present

FLVTag

Property	Type	Description
type	enum FLVTag.TagType	Type of this tag
timestamp	number	Time in milliseconds at which the data in this tag applies
data	Audio or Video	An instance of Audio / Video

Audio

Property	Type	Description
format	enum Audio.SoundFormat	Type of this tag. Only AAC is supported.
sampleRate	enum Audio.SampleRate	sample rate
size	enum Audio.SampleLength	bits per sample
isStereo	boolean	mono / stereo
data	Buffer or Uint8Array	Format specific data.

AAC extends Audio

Property	Type	Description
packetType	enum AAC.PacketType	AAC packet type

Video

Property	Type	Description
frameType	enum Video.FrameType	Type of the frame included in this tag
codec	enum Video.Codec	Type of codec used to compress the frame. Only AVC is supported.
data	Buffer or Uint8Array	Codec specific data.

AVC extends Video

Property	Type	Description
packetType	enum AVC.PacketType	AVC packet type
compositionTimeOffset	number	Composition time offset