Add new option to generate subtitles by a specific number of words (#1729)

* ADD parser for new argument --max_words_count

* ADD max_words_count in words_options
ADD warning for max_line_width compatibility

* ADD logic for max_words_count

* rename to max_words_per_line

* make them kwargs

* allow specifying file path by --model

* black formatting

---------

Co-authored-by: Jong Wook Kim <jongwook@nyu.edu>

whisper/transcribe.py

@@ -378,10 +378,17 @@ def transcribe(
 def cli():
     from . import available_models
 
+    def valid_model_name(name):
+        if name in available_models() or os.path.exists(name):
+            return name
+        raise ValueError(
+            f"model should be one of {available_models()} or path to a model checkpoint"
+        )
+
     # fmt: off
     parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter)
     parser.add_argument("audio", nargs="+", type=str, help="audio file(s) to transcribe")
-    parser.add_argument("--model", default="small", choices=available_models(), help="name of the Whisper model to use")
+    parser.add_argument("--model", default="small", type=valid_model_name, help="name of the Whisper model to use")
     parser.add_argument("--model_dir", type=str, default=None, help="the path to save model files; uses ~/.cache/whisper by default")
     parser.add_argument("--device", default="cuda" if torch.cuda.is_available() else "cpu", help="device to use for PyTorch inference")
     parser.add_argument("--output_dir", "-o", type=str, default=".", help="directory to save the outputs")
@@ -412,6 +419,7 @@ def cli():
     parser.add_argument("--highlight_words", type=str2bool, default=False, help="(requires --word_timestamps True) underline each word as it is spoken in srt and vtt")
     parser.add_argument("--max_line_width", type=optional_int, default=None, help="(requires --word_timestamps True) the maximum number of characters in a line before breaking the line")
     parser.add_argument("--max_line_count", type=optional_int, default=None, help="(requires --word_timestamps True) the maximum number of lines in a segment")
+    parser.add_argument("--max_words_per_line", type=optional_int, default=None, help="(requires --word_timestamps True, no effect with --max_line_width) the maximum number of words in a segment")
     parser.add_argument("--threads", type=optional_int, default=0, help="number of threads used by torch for CPU inference; supercedes MKL_NUM_THREADS/OMP_NUM_THREADS")
     # fmt: on
 
@@ -444,17 +452,24 @@ def cli():
     model = load_model(model_name, device=device, download_root=model_dir)
 
     writer = get_writer(output_format, output_dir)
-    word_options = ["highlight_words", "max_line_count", "max_line_width"]
+    word_options = [
+        "highlight_words",
+        "max_line_count",
+        "max_line_width",
+        "max_words_per_line",
+    ]
     if not args["word_timestamps"]:
         for option in word_options:
             if args[option]:
                 parser.error(f"--{option} requires --word_timestamps True")
     if args["max_line_count"] and not args["max_line_width"]:
         warnings.warn("--max_line_count has no effect without --max_line_width")
+    if args["max_words_per_line"] and args["max_line_width"]:
+        warnings.warn("--max_words_per_line has no effect with --max_line_width")
     writer_args = {arg: args.pop(arg) for arg in word_options}
     for audio_path in args.pop("audio"):
         result = transcribe(model, audio_path, temperature=temperature, **args)
-        writer(result, audio_path, writer_args)
+        writer(result, audio_path, **writer_args)
 
 
 if __name__ == "__main__":

whisper/utils.py

@@ -74,7 +74,9 @@ class ResultWriter:
     def __init__(self, output_dir: str):
         self.output_dir = output_dir
 
-    def __call__(self, result: dict, audio_path: str, options: dict):
+    def __call__(
+        self, result: dict, audio_path: str, options: Optional[dict] = None, **kwargs
+    ):
         audio_basename = os.path.basename(audio_path)
         audio_basename = os.path.splitext(audio_basename)[0]
         output_path = os.path.join(
@@ -82,16 +84,20 @@ class ResultWriter:
         )
 
         with open(output_path, "w", encoding="utf-8") as f:
-            self.write_result(result, file=f, options=options)
+            self.write_result(result, file=f, options=options, **kwargs)
 
-    def write_result(self, result: dict, file: TextIO, options: dict):
+    def write_result(
+        self, result: dict, file: TextIO, options: Optional[dict] = None, **kwargs
+    ):
         raise NotImplementedError
 
 
 class WriteTXT(ResultWriter):
     extension: str = "txt"
 
-    def write_result(self, result: dict, file: TextIO, options: dict):
+    def write_result(
+        self, result: dict, file: TextIO, options: Optional[dict] = None, **kwargs
+    ):
         for segment in result["segments"]:
             print(segment["text"].strip(), file=file, flush=True)
 
@@ -100,12 +106,24 @@ class SubtitlesWriter(ResultWriter):
     always_include_hours: bool
     decimal_marker: str
 
-    def iterate_result(self, result: dict, options: dict):
-        raw_max_line_width: Optional[int] = options["max_line_width"]
-        max_line_count: Optional[int] = options["max_line_count"]
-        highlight_words: bool = options["highlight_words"]
-        max_line_width = 1000 if raw_max_line_width is None else raw_max_line_width
-        preserve_segments = max_line_count is None or raw_max_line_width is None
+    def iterate_result(
+        self,
+        result: dict,
+        options: Optional[dict] = None,
+        *,
+        max_line_width: Optional[int] = None,
+        max_line_count: Optional[int] = None,
+        highlight_words: bool = False,
+        max_words_per_line: Optional[int] = None,
+    ):
+        options = options or {}
+        max_line_width = max_line_width or options.get("max_line_width")
+        max_line_count = max_line_count or options.get("max_line_count")
+        highlight_words = highlight_words or options.get("highlight_words", False)
+        max_words_per_line = max_words_per_line or options.get("max_words_per_line")
+        preserve_segments = max_line_count is None or max_line_width is None
+        max_line_width = max_line_width or 1000
+        max_words_per_line = max_words_per_line or 1000
 
         def iterate_subtitles():
             line_len = 0
@@ -114,34 +132,50 @@ class SubtitlesWriter(ResultWriter):
             subtitle: list[dict] = []
             last = result["segments"][0]["words"][0]["start"]
             for segment in result["segments"]:
-                for i, original_timing in enumerate(segment["words"]):
-                    timing = original_timing.copy()
-                    long_pause = not preserve_segments and timing["start"] - last > 3.0
-                    has_room = line_len + len(timing["word"]) <= max_line_width
-                    seg_break = i == 0 and len(subtitle) > 0 and preserve_segments
-                    if line_len > 0 and has_room and not long_pause and not seg_break:
-                        # line continuation
-                        line_len += len(timing["word"])
-                    else:
-                        # new line
-                        timing["word"] = timing["word"].strip()
+                chunk_index = 0
+                words_count = max_words_per_line
+                while chunk_index < len(segment["words"]):
+                    remaining_words = len(segment["words"]) - chunk_index
+                    if max_words_per_line > len(segment["words"]) - chunk_index:
+                        words_count = remaining_words
+                    for i, original_timing in enumerate(
+                        segment["words"][chunk_index : chunk_index + words_count]
+                    ):
+                        timing = original_timing.copy()
+                        long_pause = (
+                            not preserve_segments and timing["start"] - last > 3.0
+                        )
+                        has_room = line_len + len(timing["word"]) <= max_line_width
+                        seg_break = i == 0 and len(subtitle) > 0 and preserve_segments
                         if (
-                            len(subtitle) > 0
-                            and max_line_count is not None
-                            and (long_pause or line_count >= max_line_count)
-                            or seg_break
+                            line_len > 0
+                            and has_room
+                            and not long_pause
+                            and not seg_break
                         ):
-                            # subtitle break
-                            yield subtitle
-                            subtitle = []
-                            line_count = 1
-                        elif line_len > 0:
-                            # line break
-                            line_count += 1
-                            timing["word"] = "\n" + timing["word"]
-                        line_len = len(timing["word"].strip())
-                    subtitle.append(timing)
-                    last = timing["start"]
+                            # line continuation
+                            line_len += len(timing["word"])
+                        else:
+                            # new line
+                            timing["word"] = timing["word"].strip()
+                            if (
+                                len(subtitle) > 0
+                                and max_line_count is not None
+                                and (long_pause or line_count >= max_line_count)
+                                or seg_break
+                            ):
+                                # subtitle break
+                                yield subtitle
+                                subtitle = []
+                                line_count = 1
+                            elif line_len > 0:
+                                # line break
+                                line_count += 1
+                                timing["word"] = "\n" + timing["word"]
+                            line_len = len(timing["word"].strip())
+                        subtitle.append(timing)
+                        last = timing["start"]
+                    chunk_index += max_words_per_line
             if len(subtitle) > 0:
                 yield subtitle
 
@@ -190,9 +224,11 @@ class WriteVTT(SubtitlesWriter):
     always_include_hours: bool = False
     decimal_marker: str = "."
 
-    def write_result(self, result: dict, file: TextIO, options: dict):
+    def write_result(
+        self, result: dict, file: TextIO, options: Optional[dict] = None, **kwargs
+    ):
         print("WEBVTT\n", file=file)
-        for start, end, text in self.iterate_result(result, options):
+        for start, end, text in self.iterate_result(result, options, **kwargs):
             print(f"{start} --> {end}\n{text}\n", file=file, flush=True)
 
 
@@ -201,9 +237,11 @@ class WriteSRT(SubtitlesWriter):
     always_include_hours: bool = True
     decimal_marker: str = ","
 
-    def write_result(self, result: dict, file: TextIO, options: dict):
+    def write_result(
+        self, result: dict, file: TextIO, options: Optional[dict] = None, **kwargs
+    ):
         for i, (start, end, text) in enumerate(
-            self.iterate_result(result, options), start=1
+            self.iterate_result(result, options, **kwargs), start=1
         ):
             print(f"{i}\n{start} --> {end}\n{text}\n", file=file, flush=True)
 
@@ -220,7 +258,9 @@ class WriteTSV(ResultWriter):
 
     extension: str = "tsv"
 
-    def write_result(self, result: dict, file: TextIO, options: dict):
+    def write_result(
+        self, result: dict, file: TextIO, options: Optional[dict] = None, **kwargs
+    ):
         print("start", "end", "text", sep="\t", file=file)
         for segment in result["segments"]:
             print(round(1000 * segment["start"]), file=file, end="\t")
@@ -231,7 +271,9 @@ class WriteTSV(ResultWriter):
 class WriteJSON(ResultWriter):
     extension: str = "json"
 
-    def write_result(self, result: dict, file: TextIO, options: dict):
+    def write_result(
+        self, result: dict, file: TextIO, options: Optional[dict] = None, **kwargs
+    ):
         json.dump(result, file)
 
 
@@ -249,9 +291,11 @@ def get_writer(
     if output_format == "all":
         all_writers = [writer(output_dir) for writer in writers.values()]
 
-        def write_all(result: dict, file: TextIO, options: dict):
+        def write_all(
+            result: dict, file: TextIO, options: Optional[dict] = None, **kwargs
+        ):
             for writer in all_writers:
-                writer(result, file, options)
+                writer(result, file, options, **kwargs)
 
         return write_all