ffmpeg -i “test.flv” -ss 3 -vframes 1 -r 1 -ac 1 -ab 2 -s 160×120 -f image2 “a.jpg”
1.先到www.3gpp.org下載以下三個文件：
- http://www.3gpp.org/ftp/Specs/2004-03/Rel-5/26_series/26204-520.zip
- http://www.3gpp.org/ftp/Specs/2004-03/Rel-5/26_series/26073-530.zip
- http://www.3gpp.org/ftp/Specs/2004-03/Rel-5/26_series/26104-540.zip
分別解壓縮到以下文件夾：
- 26204-520.zip into libavcodec/amrwb_float
- 26073-530.zip into libavcodec/amr
- 26104-540.zip into libavcodec/amr_float
2.重新編譯ffmpeg，記得加上–enable-amr_nb –enable-amr_wb
3.執行以下命令即可完成轉換，具體參數含義查看man
ffmpeg -i test.avi -y -b 20 -s sqcif -r 10 -acodec amr_wb -ab 23.85 -ac 1 -ar 16000 test.3gp