ffmpeg的acodec参数可以尝试的值及解释
下表转自：https://developer.qiniu.com/dora/kb/1432/avthumb-parameter-acodec-format-and-explanation
对于ffmpeg的-acodec参数值是否适用，请自行尝试
| audioEncoders | description |
|---|---|
| aac | AAC (Advanced Audio Coding) |
| libfaac | |
| ac3 | ATSC A/52A (AC-3) |
| ac3_fixed | ATSC A/52A (AC-3) (codec ac3) |
| adpcm_adx | SEGA CRI ADX ADPCM |
| g722 | G.722 ADPCM (codec adpcm_g722) |
| g726 | G.726 ADPCM (codec adpcm_g726) |
| adpcm_ima_qt | ADPCM IMA QuickTime |
| adpcm_ima_wav | ADPCM IMA WAV |
| adpcm_ms | ADPCM Microsoft |
| adpcm_swf | ADPCM Shockwave Flash |
| adpcm_yamaha | ADPCM Yamaha |
| alac | ALAC (Apple Lossless Audio Codec) |
| libopencore_amrnb | OpenCORE AMR-NB (Adaptive Multi-Rate Narrow-Band) (codec amr_nb) |
| comfortnoise | RFC 3389 comfort noise generator |
| dca | DCA (DTS Coherent Acoustics) (codec dts) |
| eac3 | ATSC A/52 E-AC-3 |
| flac | FLAC (Free Lossless Audio Codec) |
| g723_1 | G.723.1 |
| libilbc | iLBC (Internet Low Bitrate Codec) (codec ilbc) |
| mp2 | MP2 (MPEG audio layer 2) |
| libmp3lame | libmp3lame MP3 (MPEG audio layer 3) (codec mp3) |
| nellymoser | Nellymoser Asao |
| pcm_alaw | PCM A-law / G.711 A-law |
| pcm_f32be | PCM 32-bit floating point big-endian |
| pcm_f32le | PCM 32-bit floating point little-endian |
| pcm_f64be | PCM 64-bit floating point big-endian |
| pcm_f64le | PCM 64-bit floating point little-endian |
| pcm_mulaw | PCM mu-law / G.711 mu-law |
| pcm_s16be | PCM signed 16-bit big-endian |
| pcm_s16be_planar | PCM signed 16-bit big-endian planar |
| pcm_s16le | PCM signed 16-bit little-endian |
| pcm_s16le_planar | PCM signed 16-bit little-endian planar |
| pcm_s24be | PCM signed 24-bit big-endian |
| pcm_s24daud | PCM D-Cinema audio signed 24-bit |
| pcm_s24le | PCM signed 24-bit little-endian |
| pcm_s24le_planar | PCM signed 24-bit little-endian planar |
| pcm_s32be | PCM signed 32-bit big-endian |
| pcm_s32le | PCM signed 32-bit little-endian |
| pcm_s32le_planar | PCM signed 32-bit little-endian planar |
| pcm_s8 | CM signed 8-bit |
| pcm_s8_planar | PCM signed 8-bit planar |
| pcm_u16be | PCM unsigned 16-bit big-endian |
| pcm_u16le | PCM unsigned 16-bit little-endian |
| pcm_u24be | PCM unsigned 24-bit big-endian |
| pcm_u24le | PCM unsigned 24-bit little-endian |
| pcm_u32be | PCM unsigned 32-bit big-endian |
| pcm_u32le | PCM unsigned 32-bit little-endian |
| pcm_u8 | PCM unsigned 8-bit |
| real_144 | RealAudio 1.0 (14.4K) (codec ra_144) |
| roq_dpcm | id RoQ DPCM |
| s302m | SMPTE 302M |
| sonic | Sonic |
| sonicls | Sonic lossless |
| tta | TTA (True Audio) |
| vorbis | Vorbis |
| libvorbis | ibvorbis (codec vorbis) |
| wavpack | 无损音频压缩格式 |
| wmav1 | Windows Media Audio 1 |
| wmav2 | Windows Media Audio 2 |
| copy | 编码同原始音频 |
后来发现可以用 ffmpeg -encoders来查：
D:\ffmpeg7-win32-static\bin>ffmpeg -encoders
ffmpeg version N-49044-g89afa63 Copyright (c) 2000-2013 the FFmpeg developers
built on Jan 19 2013 20:36:06 with gcc 4.7.2 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --en
libavutil 52. 15.100 / 52. 15.100
libavcodec 54. 89.100 / 54. 89.100
libavformat 54. 61.101 / 54. 61.101
libavdevice 54. 3.102 / 54. 3.102
libavfilter 3. 32.101 / 3. 32.101
libswscale 2. 2.100 / 2. 2.100
libswresample 0. 17.102 / 0. 17.102
libpostproc 52. 2.100 / 52. 2.100
Encoders:
V..... = Video
A..... = Audio
S..... = Subtitle
.F.... = Frame-level multithreading
..S... = Slice-level multithreading
...X.. = Codec is experimental
....B. = Supports draw_horiz_band
.....D = Supports direct rendering method 1
------
V..... a64multi Multicolor charset for Commodore 64 (codec a64_multi)
V..... a64multi5 Multicolor charset for Commodore 64, extended with 5th color (colram) (codec
V..... amv AMV Video
V..... asv1 ASUS V1
V..... asv2 ASUS V2
V..... avrp Avid 1:1 10-bit RGB Packer
V..X.. avui Avid Meridien Uncompressed
V..... ayuv Uncompressed packed MS 4:4:4:4
V..... bmp BMP (Windows and OS/2 bitmap)
V..... libxavs libxavs Chinese AVS (Audio Video Standard) (codec cavs)
V..... cljr Cirrus Logic AccuPak
V..... libschroedinger libschroedinger Dirac 2.2 (codec dirac)
V.S... dnxhd VC3/DNxHD
V..... dpx DPX image
V.S... dvvideo DV (Digital Video)
V.S... ffv1 FFmpeg video codec #1
V..... ffvhuff Huffyuv FFmpeg variant
V..... flashsv Flash Screen Video
V..... flashsv2 Flash Screen Video Version 2
V..... flv FLV / Sorenson Spark / Sorenson H.263 (Flash Video) (codec flv1)
V..... gif GIF (Graphics Interchange Format)
V..... h261 H.261
V..... h263 H.263 / H.263-1996
V.S... h263p H.263+ / H.263-1998 / H.263 version 2
V..... libx264 libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (codec h264)
V..... libx264rgb libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 RGB (codec h264)
V..... huffyuv Huffyuv / HuffYUV
V..X.. j2k JPEG 2000 (codec jpeg2000)
V..... libopenjpeg OpenJPEG JPEG 2000 (codec jpeg2000)
V..... jpegls JPEG-LS
V..... ljpeg Lossless JPEG
VFS... mjpeg MJPEG (Motion JPEG)
V.S... mpeg1video MPEG-1 video
V.S... mpeg2video MPEG-2 video
V.S... mpeg4 MPEG-4 part 2
V..... libxvid libxvidcore MPEG-4 part 2 (codec mpeg4)
V..... msmpeg4v2 MPEG-4 part 2 Microsoft variant version 2
V..... msmpeg4 MPEG-4 part 2 Microsoft variant version 3 (codec msmpeg4v3)
V..... msvideo1 Microsoft Video-1
V..... pam PAM (Portable AnyMap) image
V..... pbm PBM (Portable BitMap) image
V..... pcx PC Paintbrush PCX image
V..... pgm PGM (Portable GrayMap) image
V..... pgmyuv PGMYUV (Portable GrayMap YUV) image
VF.... png PNG (Portable Network Graphics) image
V..... ppm PPM (Portable PixelMap) image
VF.... prores Apple ProRes
VF.... prores_anatoliy Apple ProRes (codec prores)
V.S... prores_kostya Apple ProRes (iCodec Pro) (codec prores)
V..... qtrle QuickTime Animation (RLE) video
V..... r10k AJA Kona 10-bit RGB Codec
V..... r210 Uncompressed RGB 10-bit
V..... rawvideo raw video
V..... roqvideo id RoQ video (codec roq)
V..... rv10 RealVideo 1.0
V..... rv20 RealVideo 2.0
V..... sgi SGI image
V..... snow Snow
V..... sunrast Sun Rasterfile image
V..... svq1 Sorenson Vector Quantizer 1 / Sorenson Video 1 / SVQ1
V..... targa Truevision Targa image
V..... libtheora libtheora Theora (codec theora)
V..... tiff TIFF image
V..... utvideo Ut Video
V..... v210 Uncompressed 4:2:2 10-bit
V..... v308 Uncompressed packed 4:4:4
V..... v408 Uncompressed packed QT 4:4:4:4
V..... v410 Uncompressed 4:4:4 10-bit
V..... libvpx libvpx VP8 (codec vp8)
V..... wmv1 Windows Media Video 7
V..... wmv2 Windows Media Video 8
V..... xbm XBM (X BitMap) image
V..... xface X-face image
V..... xwd XWD (X Window Dump) image
V..... y41p Uncompressed YUV 4:1:1 12-bit
V..... yuv4 Uncompressed packed 4:2:0
V..... zlib LCL (LossLess Codec Library) ZLIB
V..... zmbv Zip Motion Blocks Video
A..X.. aac AAC (Advanced Audio Coding)
A..... libvo_aacenc Android VisualOn AAC (Advanced Audio Coding) (codec aac)
A..... ac3 ATSC A/52A (AC-3)
A..... ac3_fixed ATSC A/52A (AC-3) (codec ac3)
A..... adpcm_adx SEGA CRI ADX ADPCM
A..... g722 G.722 ADPCM (codec adpcm_g722)
A..... g726 G.726 ADPCM (codec adpcm_g726)
A..... adpcm_ima_qt ADPCM IMA QuickTime
A..... adpcm_ima_wav ADPCM IMA WAV
A..... adpcm_ms ADPCM Microsoft
A..... adpcm_swf ADPCM Shockwave Flash
A..... adpcm_yamaha ADPCM Yamaha
A..... alac ALAC (Apple Lossless Audio Codec)
A..... libopencore_amrnb OpenCORE AMR-NB (Adaptive Multi-Rate Narrow-Band) (codec amr_nb)
A..... libvo_amrwbenc Android VisualOn AMR-WB (Adaptive Multi-Rate Wide-Band) (codec amr_wb)
A..... comfortnoise RFC 3389 comfort noise generator
A..X.. dca DCA (DTS Coherent Acoustics) (codec dts)
A..... eac3 ATSC A/52 E-AC-3
A..... flac FLAC (Free Lossless Audio Codec)
A..... g723_1 G.723.1
A..... libgsm libgsm GSM (codec gsm)
A..... libgsm_ms libgsm GSM Microsoft variant (codec gsm_ms)
A..... mp2 MP2 (MPEG audio layer 2)
A..... libtwolame libtwolame MP2 (MPEG audio layer 2) (codec mp2)
A..... libmp3lame libmp3lame MP3 (MPEG audio layer 3) (codec mp3)
A..... nellymoser Nellymoser Asao
A..... libopus libopus Opus (codec opus)
A..... pcm_alaw PCM A-law / G.711 A-law
A..... pcm_f32be PCM 32-bit floating point big-endian
A..... pcm_f32le PCM 32-bit floating point little-endian
A..... pcm_f64be PCM 64-bit floating point big-endian
A..... pcm_f64le PCM 64-bit floating point little-endian
A..... pcm_mulaw PCM mu-law / G.711 mu-law
A..... pcm_s16be PCM signed 16-bit big-endian
A..... pcm_s16be_planar PCM signed 16-bit big-endian planar
A..... pcm_s16le PCM signed 16-bit little-endian
A..... pcm_s16le_planar PCM signed 16-bit little-endian planar
A..... pcm_s24be PCM signed 24-bit big-endian
A..... pcm_s24daud PCM D-Cinema audio signed 24-bit
A..... pcm_s24le PCM signed 24-bit little-endian
A..... pcm_s24le_planar PCM signed 24-bit little-endian planar
A..... pcm_s32be PCM signed 32-bit big-endian
A..... pcm_s32le PCM signed 32-bit little-endian
A..... pcm_s32le_planar PCM signed 32-bit little-endian planar
A..... pcm_s8 PCM signed 8-bit
A..... pcm_s8_planar PCM signed 8-bit planar
A..... pcm_u16be PCM unsigned 16-bit big-endian
A..... pcm_u16le PCM unsigned 16-bit little-endian
A..... pcm_u24be PCM unsigned 24-bit big-endian
A..... pcm_u24le PCM unsigned 24-bit little-endian
A..... pcm_u32be PCM unsigned 32-bit big-endian
A..... pcm_u32le PCM unsigned 32-bit little-endian
A..... pcm_u8 PCM unsigned 8-bit
A..... real_144 RealAudio 1.0 (14.4K) (codec ra_144)
A..... roq_dpcm id RoQ DPCM
A..X.. sonic Sonic
A..X.. sonicls Sonic lossless
A..... libspeex libspeex Speex (codec speex)
A..X.. vorbis Vorbis
A..... libvorbis libvorbis (codec vorbis)
A..... wmav1 Windows Media Audio 1
A..... wmav2 Windows Media Audio 2
S..... dvbsub DVB subtitles (codec dvb_subtitle)
S..... dvdsub DVD subtitles (codec dvd_subtitle)
S..... mov_text 3GPP Timed Text subtitle
S..... srt SubRip subtitle with embedded timing
S..... ass SSA (SubStation Alpha) subtitle (codec ssa)
S..... subrip SubRip subtitle
S..... xsub DivX subtitles (XSUB)