av/container/mts/audio_test.go

/*
NAME
  audio_test.go

AUTHOR
  Trek Hopton <trek@ausocean.org>

LICENSE
  audio_test.go is Copyright (C) 2017-2019 the Australian Ocean Lab (AusOcean)

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 for more details.

  You should have received a copy of the GNU General Public License in gpl.txt.
  If not, see http://www.gnu.org/licenses.
*/

package mts

import (
	"bytes"
	"io"
	"io/ioutil"
	"testing"

	"github.com/Comcast/gots/packet"
	"github.com/Comcast/gots/pes"

	"bitbucket.org/ausocean/av/container/mts/meta"
)

type nopCloser struct{ io.Writer }

func (nopCloser) Close() error { return nil }

// TestEncodePcm tests the mpegts encoder's ability to encode pcm audio data.
// It reads and encodes input pcm data into mpegts, then decodes the mpegts and compares the result to the input pcm.
func TestEncodePcm(t *testing.T) {
	Meta = meta.New()

	var buf bytes.Buffer
	sampleRate := 48000
	sampleSize := 2
	chunkSize := 16000
	writeFreq := float64(sampleRate*sampleSize) / float64(chunkSize)
	e := NewEncoder(nopCloser{&buf}, writeFreq, Audio)

	inPath := "../../../test/test-data/av/input/sweep_400Hz_20000Hz_-3dBFS_5s_48khz.pcm"
	inPcm, err := ioutil.ReadFile(inPath)
	if err != nil {
		t.Errorf("unable to read file: %v", err)
	}

	// Break pcm into blocks and encode to mts and get the resulting bytes.
	for i := 0; i < len(inPcm); i += chunkSize {
		if len(inPcm)-i < chunkSize {
			block := inPcm[i:]
			_, err = e.Write(block)
			if err != nil {
				t.Errorf("unable to write block: %v", err)
			}
		} else {
			block := inPcm[i : i+chunkSize]
			_, err = e.Write(block)
			if err != nil {
				t.Errorf("unable to write block: %v", err)
			}
		}
	}
	clip := buf.Bytes()

	// Get the first MTS packet to check
	var pkt packet.Packet
	pesPacket := make([]byte, 0, chunkSize)
	got := make([]byte, 0, len(inPcm))
	i := 0
	if i+PacketSize <= len(clip) {
		copy(pkt[:], clip[i:i+PacketSize])
	}

	// Loop through MTS packets until all the audio data from PES packets has been retrieved
	for i+PacketSize <= len(clip) {

		// Check MTS packet
		if !(pkt.PID() == AudioPid) {
			i += PacketSize
			if i+PacketSize <= len(clip) {
				copy(pkt[:], clip[i:i+PacketSize])
			}
			continue
		}
		if !pkt.PayloadUnitStartIndicator() {
			i += PacketSize
			if i+PacketSize <= len(clip) {
				copy(pkt[:], clip[i:i+PacketSize])
			}
		} else {
			// Copy the first MTS payload
			payload, err := pkt.Payload()
			if err != nil {
				t.Errorf("unable to get MTS payload: %v", err)
			}
			pesPacket = append(pesPacket, payload...)

			i += PacketSize
			if i+PacketSize <= len(clip) {
				copy(pkt[:], clip[i:i+PacketSize])
			}

			// Copy the rest of the MTS payloads that are part of the same PES packet
			for (!pkt.PayloadUnitStartIndicator()) && i+PacketSize <= len(clip) {
				payload, err = pkt.Payload()
				if err != nil {
					t.Errorf("unable to get MTS payload: %v", err)
				}
				pesPacket = append(pesPacket, payload...)

				i += PacketSize
				if i+PacketSize <= len(clip) {
					copy(pkt[:], clip[i:i+PacketSize])
				}
			}
		}
		// Get the audio data from the current PES packet
		pesHeader, err := pes.NewPESHeader(pesPacket)
		if err != nil {
			t.Errorf("unable to read PES packet: %v", err)
		}
		got = append(got, pesHeader.Data()...)
		pesPacket = pesPacket[:0]
	}

	// Compare data from MTS with original data.
	if !bytes.Equal(got, inPcm) {
		t.Error("data decoded from mts did not match input data")
	}
}