构建音乐收藏库
主推FLAC无损压缩格式，有损的话常见的有MP3, 不常见的有个Opus。
构建方式
电脑端存储一份FLAC，手机上存一份MP3/Opus。
音乐来源
- Bandcamp
- 网易云音乐
FLAC、MP3和Opus
| 维度 | FLAC (无损) | Opus (现代有损) | MP3 (传统有损) |
|---|---|---|---|
| 核心定位 | 母带存档、高保真 | 移动/网络/语音 | 全设备兼容 |
| 文件体积 | 大 (5MB/分钟) | 极小 (2MB/分钟@192k) | 中 (3.5MB/分钟@192k) |
| 典型码率 | 500-1100 kbps | 64-192 kbps | 128-320 kbps |
| 等效音质码率 | - | 128kbps ≈ MP3 192kbps | 192kbps (良好) |
| 压缩效率 | 50-60% (无损) | 优于MP3 30-50% | 基准 |
| 专利状态 | 开源免费 | 免专利费 | 专利已过期 (2017) |
FLAC转Opus
ffmpeg -y -loglevel 'error' -i '*.flac' -vn -acodec libopus -b:a 64k '*.opus'
| 参数 | 含义 | 说明 |
|---|---|---|
-y | 覆盖输出 | 若目标文件已存在，直接覆盖不提示 |
-loglevel 'error' | 日志级别 | 仅显示错误信息，屏蔽转码过程的详细信息 |
-i '...flac' | 输入文件 | 指定源FLAC音频文件 |
-vn | 禁用视频 | 不处理可能存在的视频/封面流（纯音频场景） |
-acodec libopus | 音频编码器 | 使用Opus编码器（高质量有损压缩） |
-b:a 96k | 音频比特率 | 设置输出码率为96kbps（每秒96千比特） |
'...opus' | 输出文件 | 生成的Opus格式文件名 |
比特率不同值差异
来源：https://wiki.hydrogenaudio.org/?title=Opus#Music_encoding_quality
| Bitrate target | Stereo mode | Bandwidth | typ SILK/CELT use | Music quality notes | Use cases/notes/competitive codecs |
|---|---|---|---|---|---|
| 4 kbps | mono | 6 kHz | SILK | Poor, muffled sound but intelligible lyrics. | — |
| 9 kbps | mono | 8 kHz | SILK | Poor, muffled but OK for bitrate | — |
| 14 to 16 kbps | mono | 20 kHz | hybrid/CELT | Fairly poor but OK for bitrate | Perhaps acceptable for incidental music |
| 22 to 24 kbps | mono | 20 kHz | hybrid/CELT | Fair but OK for bitrate | OK for incidental music |
| 32 to 40 kbps | stereo | 20 kHz | CELT | Moderately good stereo, some artifacts, rarely nasty | Stereo podcasts, audiobooks, very low bitrate music |
| 48 kbps | stereo | 20 kHz | CELT | Full bandwidth stereo music, nice sound, may have problems with cymbals | Stereo podcasts, audiobooks, low bitrate music |
| 64 kbps | stereo | 20 kHz | CELT | Full bandwidth stereo music, nice sound, detectable differences to original (mostly 'not annoying') | Music storage & streaming. Beat HE-AAC, Vorbis, MP3 in listening test |
| 96 kbps | stereo | 20 kHz | CELT | Full bandwidth stereo music, good quality approaching transparency | Music storage & high quality streaming. Beat LC-AAC, Vorbis, MP3 in listening test |
| 112 kbps | stereo | 20 kHz | CELT | Fairly close to transparency (needs more testing) | Music storage & high quality streaming. Very low-latency stereo networked music performance/jam sessions at OK quality |
| 128 kbps | stereo | 20 kHz | CELT | Very close to transparency (needs more testing). Most modern codecs competitive (AAC-LC, Vorbis, MP3) | Music storage & streaming. Future download music sales. |
| 160 to 192 kbps | stereo | 20 kHz | CELT | Transparent with very low chance of artifacts (a few killer samples still detectable). Most old & new lossy codecs competitive. | Music storage & streaming, dedicated limited-bandwidth audio links (e.g. wireless, A2DP-bluetooth type links). |
| 510 kbps | stereo | 20 kHz | CELT | Maximum possible stereo bitrate target (actual rate often less than 510 for default frame size). Most old and new lossy codecs competitive, plus near-lossless lossyWAV and WavPack lossy | Music storage, dedicated limited-bitrate audio links (e.g. wireless, minimum latency high quality audio. LossyWAV and WavPack lossy are very competitive for storage, and WavPack lossy 256 may be competitive with minimum latency mode also. |
| >510 kbps | — | — | — | Above Opus bitrate range allowed for stereo sources | Settle for 510 kbps or use lossless, lossyWAV, WavPack lossy or lossy transform/subband codecs like Vorbis, Musepack at very high settings. |