Add Multilingual Transcription Support to 'GetTranscript()' Function

client.go

@@ -215,10 +215,10 @@ func (c *Client) videoDataByInnertube(ctx context.Context, id string) ([]byte, e
 	return c.httpPostBodyBytes(ctx, "https://www.youtube.com/youtubei/v1/player?key="+c.client.key, data)
 }
 
-func (c *Client) transcriptDataByInnertube(ctx context.Context, id string) ([]byte, error) {
+func (c *Client) transcriptDataByInnertube(ctx context.Context, id string, lang string) ([]byte, error) {
 	data := innertubeRequest{
 		Context: prepareInnertubeContext(*c.client),
-		Params:  transcriptVideoID(id),
+		Params:  transcriptVideoID(id, lang),
 	}
 
 	return c.httpPostBodyBytes(ctx, "https://www.youtube.com/youtubei/v1/get_transcript?key="+c.client.key, data)
@@ -261,8 +261,8 @@ func prepareInnertubePlaylistData(ID string, continuation bool, clientInfo clien
 }
 
 // transcriptVideoID encodes the video ID to the param used to fetch transcripts.
-func transcriptVideoID(videoID string) string {
-	langCode := encTranscriptLang("en")
+func transcriptVideoID(videoID string, lang string) string {
+	langCode := encTranscriptLang(lang)
 
 	// This can be optionally appened to the Sprintf str, not sure what it means
 	// *3engagement-panel-searchable-transcript-search-panel\x30\x00\x38\x01\x40\x01

transcript.go

@@ -47,22 +47,22 @@ func (vt VideoTranscript) String() string {
 //
 // Not all videos have transcripts, only relatively new videos.
 // If transcripts are disabled or not available, ErrTranscriptDisabled is returned.
-func (c *Client) GetTranscript(video *Video) (VideoTranscript, error) {
-	return c.GetTranscriptCtx(context.Background(), video)
+func (c *Client) GetTranscript(video *Video, lang string) (VideoTranscript, error) {
+	return c.GetTranscriptCtx(context.Background(), video, lang)
 }
 
 // GetTranscriptCtx fetches the video transcript if available.
 //
 // Not all videos have transcripts, only relatively new videos.
 // If transcripts are disabled or not available, ErrTranscriptDisabled is returned.
-func (c *Client) GetTranscriptCtx(ctx context.Context, video *Video) (VideoTranscript, error) {
+func (c *Client) GetTranscriptCtx(ctx context.Context, video *Video, lang string) (VideoTranscript, error) {
 	c.assureClient()
 
 	if video == nil || video.ID == "" {
 		return nil, fmt.Errorf("no video provided")
 	}
 
-	body, err := c.transcriptDataByInnertube(ctx, video.ID)
+	body, err := c.transcriptDataByInnertube(ctx, video.ID, lang)
 	if err != nil {
 		return nil, err
 	}

transcript_test.go

@@ -10,7 +10,29 @@ import (
 func TestTranscript(t *testing.T) {
 	video := &Video{ID: "9_MbW9FK1fA"}
 
-	transcript, err := testClient.GetTranscript(video)
+	transcript, err := testClient.GetTranscript(video, "en")
+	require.NoError(t, err, "get transcript")
+	require.Greater(t, len(transcript), 0, "no transcript segments found")
+
+	for i, segment := range transcript {
+		index := strconv.Itoa(i)
+
+		require.NotEmpty(t, segment.Text, "text "+index)
+		require.NotEmpty(t, segment.Duration, "duration "+index)
+		require.NotEmpty(t, segment.OffsetText, "offset "+index)
+
+		if i != 0 {
+			require.NotEmpty(t, segment.StartMs, "startMs "+index)
+		}
+	}
+
+	t.Log(transcript.String())
+}
+
+func TestTranscriptOtherLanguage(t *testing.T) {
+	video := &Video{ID: "AXwDvYh2-uk"}
+
+	transcript, err := testClient.GetTranscript(video, "id")
 	require.NoError(t, err, "get transcript")
 	require.Greater(t, len(transcript), 0, "no transcript segments found")
 

video_test.go

@@ -31,7 +31,7 @@ func TestSimpleTest(t *testing.T) {
 	video, err := testClient.GetVideo("https://www.youtube.com/watch?v=9_MbW9FK1fA")
 	require.NoError(t, err, "get body")
 
-	_, err = testClient.GetTranscript(video)
+	_, err = testClient.GetTranscript(video, "en")
 	require.NoError(t, err, "get transcript")
 
 	// Typically youtube only provides separate streams for video and audio.