如何计算 Swift 中给定 AVURLAsset 中音频/字幕轨道的数量？

Question

我想计算给定 AVURLAsset 中音频和字幕轨道的数量。我如何使用 Swift 做到这一点？

对于给定的清单预期答案应该是 2 个字幕和 3 个音轨

#EXTM3U
#EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subtitle",NAME="#1 Fre",DEFAULT=YES,FORCED=NO,LANGUAGE="fre",URI="subtitles/planete_interdite_subtitle3_fre_vtt.m3u8"
#EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subtitle",NAME="#3 Eng",DEFAULT=NO,FORCED=NO,LANGUAGE="eng",URI="subtitles/planete_interdite_subtitle5_eng_vtt.m3u8"
#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="hdready",NAME="#2 Eng",DEFAULT=NO,AUTOSELECT=YES,LANGUAGE="eng",URI="hdready/planete_interdite_4160_n264_720p_audio2_eng.m3u8"
#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="fullhd",NAME="#1 Fre",DEFAULT=YES,AUTOSELECT=YES,LANGUAGE="fre",URI="fullhd/planete_interdite_8256_n264_1080p_audio1_fre.m3u8"
#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="fullhd",NAME="#2 Eng",DEFAULT=NO,AUTOSELECT=YES,LANGUAGE="eng",URI="fullhd/planete_interdite_8256_n264_1080p_audio2_eng.m3u8"
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=314000,CODECS="avc1.66.30,mp4a.40.2",RESOLUTION=256x144,AUDIO="low",SUBTITLES="subtitle"low/planete_interdite_228_h264_144p.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=638000,CODECS="avc1.66.30,mp4a.40.2",RESOLUTION=426x240,AUDIO="medium",SUBTITLES="subtitle"medium/planete_interdite_500_h264_240p.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=1942000,CODECS="avc1.66.30,mp4a.40.2",RESOLUTION=640x360,AUDIO="high",SUBTITLES="subtitle"high/planete_interdite_1228_q264_360p.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=3274000,CODECS="avc1.66.30,mp4a.40.2",RESOLUTION=854x480,AUDIO="veryhigh",SUBTITLES="subtitle"veryhigh/planete_interdite_2080_q264_480p.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=4814000,CODECS="avc1.4d001f,mp4a.40.2",RESOLUTION=1280x720,AUDIO="hdready",SUBTITLES="subtitle"hdready/planete_interdite_4160_n264_720p.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=9501000,CODECS="avc1.640028,mp4a.40.2",RESOLUTION=1920x1080,AUDIO="fullhd",SUBTITLES="subtitle"fullhd/planete_interdite_8256_n264_1080p.m3u8

谢谢

Answer 1

看来您需要使用函数AVAsset.tracks()：

func tracks(withMediaType mediaType: AVMediaType) -> [AVAssetTrack]

然后您可以从他们提供的here 选择中指定mediaType 参数。从您可以指定的内容来看，您似乎必须使用AVMediaType.audio 和AVMediaType.subtitle。

即获取音轨数量

var audioTracks = YourAVURLAsset.tracks(AVMediaType.audio);
var nAudioTracks = audioTracks.count;

或字幕轨道的数量

var subtitleTracks = YourAVURLAsset.tracks(AVMediaType.subtitle);
var nSubtitleTracks = var subtitleTracks.count;

注意： 代码未经测试，因此可能需要稍作调整，但希望这能让你朝着正确的方向前进