sun_
98 lines
2.5 KiB
Swift
98 lines
2.5 KiB
Swift
//
|
|
// encode_audio.swift
|
|
// Demo
|
|
//
|
|
// Created by sunlubo on 2018/7/3.
|
|
//
|
|
|
|
import Foundation
|
|
import SwiftFFmpeg
|
|
|
|
#if canImport(Darwin)
|
|
import Darwin
|
|
#else
|
|
import Glibc
|
|
#endif
|
|
|
|
private func encode(
|
|
codecCtx: AVCodecContext,
|
|
frame: AVFrame?,
|
|
pkt: AVPacket,
|
|
file: UnsafeMutablePointer<FILE>
|
|
) throws {
|
|
// send the frame for encoding
|
|
try codecCtx.sendFrame(frame)
|
|
|
|
// read all the available output packets (in general there may be any number of them)
|
|
while true {
|
|
do {
|
|
try codecCtx.receivePacket(pkt)
|
|
} catch let err as AVError where err == .tryAgain || err == .eof {
|
|
return
|
|
}
|
|
|
|
fwrite(pkt.data, 1, pkt.size, file)
|
|
pkt.unref()
|
|
}
|
|
}
|
|
|
|
func encode_audio() throws {
|
|
if CommandLine.argc < 3 {
|
|
print("Usage: \(CommandLine.arguments[0]) \(CommandLine.arguments[1]) output_file")
|
|
return
|
|
}
|
|
|
|
let output = CommandLine.arguments[2]
|
|
// find the MP2 encoder
|
|
let codec = AVCodec.findEncoderById(.MP2)!
|
|
let codecCtx = AVCodecContext(codec: codec)
|
|
|
|
// set sample parameters
|
|
codecCtx.bitRate = 64000
|
|
codecCtx.sampleFormat = .int16
|
|
codecCtx.sampleRate = 44100
|
|
codecCtx.channelLayout = AVChannelLayoutStereo
|
|
|
|
try codecCtx.openCodec()
|
|
|
|
guard let file = fopen(output, "wb") else {
|
|
fatalError("Could not open \(output)")
|
|
}
|
|
defer { fclose(file) }
|
|
|
|
// packet for holding encoded output
|
|
let pkt = AVPacket()
|
|
|
|
// frame containing input raw audio
|
|
let frame = AVFrame()
|
|
frame.sampleCount = codecCtx.frameSize
|
|
frame.sampleFormat = codecCtx.sampleFormat
|
|
frame.channelLayout = codecCtx.channelLayout
|
|
// allocate the data buffers
|
|
try frame.allocBuffer()
|
|
|
|
// encode a single tone sound
|
|
var t = 0 as Float
|
|
let tincr = Float(2 * Double.pi * 440 / Double(codecCtx.sampleRate))
|
|
for _ in 0 ..< 200 {
|
|
// make sure the frame is writable -- makes a copy if the encoder kept a reference internally
|
|
try frame.makeWritable()
|
|
|
|
let capacity = frame.sampleCount * frame.channelLayout.channelCount
|
|
let samples = UnsafeMutableRawPointer(frame.data[0]!).bindMemory(
|
|
to: UInt16.self, capacity: capacity
|
|
)
|
|
for i in 0 ..< frame.sampleCount {
|
|
let sample = UInt16(truncatingIfNeeded: Int32((sin(Double(t)) * 10000).rounded(.towardZero)))
|
|
for j in 0 ..< frame.channelLayout.channelCount {
|
|
samples[i * 2 + j] = sample
|
|
}
|
|
t += tincr
|
|
}
|
|
try encode(codecCtx: codecCtx, frame: frame, pkt: pkt, file: file)
|
|
}
|
|
|
|
// flush the encoder1
|
|
try encode(codecCtx: codecCtx, frame: nil, pkt: pkt, file: file)
|
|
}
|