Add start and end flag

README.md

@@ -13,14 +13,14 @@ https://github.com/jybp/twitch-downloader/releases
 
 ## Flags
 
-`-client-id` Use a specific twitch.tv API client ID. Usage is optional. 
-Note: Using any other client id other than twitch own client id might not work.
-
-`-o` Path where the VOD will be downloaded. Usage is optional.
-
-`-q` Quality of the VOD to download. Omit this flag to print the available qualities.
-
-`-vod` The ID or absolute URL of the twitch VOD to download. https://www.twitch.tv/videos/12345 is the VOD with ID "12345".
+|       Flag      | Description |
+| --- | --- |
+| `-vod` | The ID or absolute URL of the twitch VOD to download. https://www.twitch.tv/videos/12345 is the VOD with ID "12345". |
+| `-q` | Quality of the VOD to download. Omit this flag to print the available qualities. |
+| `-o` | Path where the VOD will be downloaded. (optional)|
+| `-start` | Specify "start" to download a subset of the VOD. Example: 1h23m45s (optional) |
+| `-end` | Specify "end" to download a subset of the VOD. Example: 1h34m56s (optional) |
+| `-client-id` | Use a specific twitch.tv API client ID. Using any other client id other than twitch own client id might not work. (optional) |
 
 ## Build from source
 

cmd/twitchdl/main.go

@@ -23,15 +23,17 @@ var defaultClientID string
 
 // Flags
 var clientID, vodID, quality, output string
+var start, end time.Duration
 
 func init() {
 	log.SetFlags(0)
 
-	flag.StringVar(&clientID, "client-id", "", "Use a specific twitch.tv API client ID. Usage is optional.")
-	flag.StringVar(&output, "o", "", `Path where the VOD will be downloaded. Usage is optional.`)
+	flag.StringVar(&vodID, "vod", "", `The ID or absolute URL of the twitch VOD to download. https://www.twitch.tv/videos/12345 is the VOD with ID "12345".`)
 	flag.StringVar(&quality, "q", "", "Quality of the VOD to download. Omit this flag to print the available qualities.")
-	flag.StringVar(&vodID, "vod", "", `The ID or absolute URL of the twitch VOD to download.
-https://www.twitch.tv/videos/12345 is the VOD with ID "12345".`)
+	flag.StringVar(&output, "o", "", `Path where the VOD will be downloaded. (optional)`)
+	flag.DurationVar(&start, "start", time.Duration(0), "Specify \"start\" to download a subset of the VOD. Example: 1h23m45s (optional)")
+	flag.DurationVar(&end, "end", time.Duration(0), "Specify \"end\" to download a subset of the VOD. Example: 1h34m56s (optional)")
+	flag.StringVar(&clientID, "client-id", "", "Use a specific twitch.tv API client ID. (optional)")
 	flag.Parse()
 }
 
@@ -69,7 +71,7 @@ func main() {
 		return
 	}
 
-	download, err := twitchdl.Download(context.Background(), http.DefaultClient, defaultClientID, vodID, quality)
+	download, err := twitchdl.Download(context.Background(), http.DefaultClient, defaultClientID, vodID, quality, start, end)
 	if err != nil {
 		log.Fatalf("Retrieving stream for VOD %s failed: %v", vodID, err)
 	}

download.go

@@ -3,8 +3,11 @@ package twitchdl
 import (
 	"bytes"
 	"context"
+	"fmt"
 	"io"
+	"math"
 	"net/http"
+	"time"
 
 	"github.com/jybp/twitch-downloader/m3u8"
 	"github.com/jybp/twitch-downloader/twitch"
@@ -34,7 +37,7 @@ func Qualities(ctx context.Context, client *http.Client, clientID, vodID string)
 // Download sets up the download of the VOD "vodId" with quality "quality"
 // using the provided http.Client.
 // The download is actually perfomed when the returned io.Reader is being read.
-func Download(ctx context.Context, client *http.Client, clientID, vodID, quality string) (r *Merger, err error) {
+func Download(ctx context.Context, client *http.Client, clientID, vodID, quality string, start, end time.Duration) (r *Merger, err error) {
 	api := twitch.New(client, clientID)
 	m3u8raw, err := api.M3U8(ctx, vodID)
 	if err != nil {
@@ -72,7 +75,11 @@ L:
 	}
 
 	var downloadFns []downloadFunc
-	for _, segment := range media.Segments {
+	segments, err := sliceSegments(media.Segments, start, end)
+	if err != nil {
+		return nil, err
+	}
+	for _, segment := range segments {
 		req, err := http.NewRequest(http.MethodGet, segment.URL, nil)
 		if err != nil {
 			return nil, errors.WithStack(err)
@@ -83,6 +90,43 @@ L:
 	return &Merger{downloads: downloadFns}, nil
 }
 
+func sliceSegments(segments []m3u8.MediaSegment, start, end time.Duration) ([]m3u8.MediaSegment, error) {
+	if start < 0 || end < 0 {
+		return nil, errors.New("Negative timestamps are not allowed")
+	}
+	if start >= end && end != time.Duration(0) {
+		return nil, errors.New("End timestamp is not after Start timestamp")
+	}
+	if start == time.Duration(0) && end == time.Duration(0) {
+		return segments, nil
+	}
+	if end == time.Duration(0) {
+		end = time.Duration(math.MaxInt64)
+	}
+	slice := []m3u8.MediaSegment{}
+	segmentStart := time.Duration(0)
+	for _, segment := range segments {
+		segmentEnd := segmentStart + segment.Duration
+		if segmentEnd <= start {
+			segmentStart += segment.Duration
+			continue
+		}
+		if segmentStart >= end {
+			break
+		}
+		slice = append(slice, segment)
+		segmentStart += segment.Duration
+	}
+	if len(slice) == 0 {
+		var dur time.Duration
+		for _, segment := range segments {
+			dur += segment.Duration
+		}
+		return nil, fmt.Errorf("Timestamps are not a subset of the video (video duration is %v)", dur)
+	}
+	return slice, nil
+}
+
 // downloadFunc describes a func that peform an HTTP request and returns the response.Body
 type downloadFunc func() (io.ReadCloser, error)
 

download_test.go

@@ -0,0 +1,94 @@
+package twitchdl
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/jybp/twitch-downloader/m3u8"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSliceSegments(t *testing.T) {
+
+	segments := []m3u8.MediaSegment{
+		{Number: 0, Duration: time.Second * 5},
+		{Number: 1, Duration: time.Second * 5},
+		{Number: 2, Duration: time.Second * 5},
+		{Number: 3, Duration: time.Second * 5},
+	}
+
+	tcs := []struct {
+		start       time.Duration
+		end         time.Duration
+		expected    []int
+		expectedErr bool
+	}{
+		{
+			start:       time.Second * 2,
+			end:         time.Second,
+			expectedErr: true,
+		},
+		{
+			start:       time.Second * 8,
+			end:         time.Second * 8,
+			expectedErr: true,
+		},
+		{
+			start:       -time.Second * 2,
+			end:         -time.Second,
+			expectedErr: true,
+		},
+		{
+			start:       time.Second * 20,
+			end:         time.Second * 21,
+			expectedErr: true,
+		},
+		{
+			start:    time.Duration(0),
+			end:      time.Duration(0),
+			expected: []int{0, 1, 2, 3},
+		},
+		{
+			start:    time.Second * 5,
+			end:      time.Duration(0),
+			expected: []int{1, 2, 3},
+		},
+		{
+			start:    time.Duration(0),
+			end:      time.Second * 5,
+			expected: []int{0},
+		},
+		{
+			start:    time.Second * 6,
+			end:      time.Second * 10,
+			expected: []int{1},
+		},
+		{
+			start:    time.Second * 6,
+			end:      time.Second * 11,
+			expected: []int{1, 2},
+		},
+		{
+			start:    time.Second * 6,
+			end:      time.Second * 22,
+			expected: []int{1, 2, 3},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(fmt.Sprintf("start: %v end: %v", tc.start, tc.end), func(t *testing.T) {
+			actual, err := sliceSegments(segments, tc.start, tc.end)
+			if tc.expectedErr {
+				require.Error(t, err)
+				return
+			}
+			require.NoError(t, err)
+			assert.Len(t, actual, len(tc.expected))
+			for i := 0; i < len(actual); i++ {
+				assert.Equal(t, tc.expected[i], actual[i].Number)
+			}
+		})
+	}
+}

go.mod

@@ -3,6 +3,10 @@ module github.com/jybp/twitch-downloader
 go 1.12
 
 require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/kr/pretty v0.1.0 // indirect
 	github.com/pkg/errors v0.8.1
 	github.com/stretchr/testify v1.4.0
+	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
 )

go.sum

@@ -1,13 +1,25 @@
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=