如何获取 Django 中 FileField 的音频持续时间？

Question

考虑使用这个模型：

class MusicTrack(models.Model):
    """
    Represents a music track
    """

    title = models.CharField("Track title", max_length=300)
    audio_file = models.FileField("Audio file", upload_to='audio/%Y-%m-%d/')

    duration_seconds = models.PositiveIntegerField("Track duration ins seconds", blank=True, null=True)

    def __str__(self):
        return f"Music track \"{self.title}\""

如何获取以秒为单位的音频持续时间并将其保存在数据库中？

Answer 1

您可以使用诱变剂来获取音频信息，例如持续时间。

要保存它，您可以将pre_save信号连接到 django 模型并更新该duration_seconds字段。最好仅在更新实际文件时执行此操作，以减少磁盘 I/O 并提高性能。

信号接收器代码将是这样的：

# considering model has audio_field = FileField()       
import mutagen

def some_pre_save_receiver(sender, instance, raw, using, update_fields, **kwargs):

    file_was_updated = False
    if hasattr(instance.audio_file, 'file') and isinstance(instance.audio_file.file, UploadedFile):
        file_was_updated = True

    if update_fields and "audio_file" in update_fields:
        file_was_updated = True          

    if file_was_updated:
        # read audio file metadata
        audio_info = mutagen.File(instance.audio_file).info
        # set audio duration in seconds, so we can access it in database
        instance.duration_seconds = int(audio_info.length)

        print(">> audio duration was was updated")

    else:
        print(">> file not changed - duration was NOT updated")