G.726實時RTP音頻流保存到AVI文件中

ffmpeg的G726包括AV_CODEC_ID_ADPCM_G726LE和AV_CODEC_ID_ADPCM_G726，即小端和大端。

在avienc.c中,codec_tag設置了音視頻封裝成avi文件所支持的音視頻編碼

 

const AVCodecTag ff_codec_wav_tags[] = {
    { AV_CODEC_ID_PCM_S16LE,       0x0001 },
    /* must come after s16le in this list */
    { AV_CODEC_ID_PCM_U8,          0x0001 },
    { AV_CODEC_ID_PCM_S24LE,       0x0001 },
    { AV_CODEC_ID_PCM_S32LE,       0x0001 },
    { AV_CODEC_ID_PCM_S64LE,       0x0001 },
    { AV_CODEC_ID_ADPCM_MS,        0x0002 },
    { AV_CODEC_ID_PCM_F32LE,       0x0003 },
    /* must come after f32le in this list */
    { AV_CODEC_ID_PCM_F64LE,       0x0003 },
    { AV_CODEC_ID_PCM_ALAW,        0x0006 },
    { AV_CODEC_ID_PCM_MULAW,       0x0007 },
    { AV_CODEC_ID_WMAVOICE,        0x000A },
    { AV_CODEC_ID_ADPCM_IMA_OKI,   0x0010 },
    { AV_CODEC_ID_ADPCM_IMA_WAV,   0x0011 },
    /* must come after adpcm_ima_wav in this list */
    { AV_CODEC_ID_PCM_ZORK,        0x0011 },
    { AV_CODEC_ID_ADPCM_IMA_OKI,   0x0017 },
    { AV_CODEC_ID_ADPCM_YAMAHA,    0x0020 },
    { AV_CODEC_ID_TRUESPEECH,      0x0022 },
    { AV_CODEC_ID_GSM_MS,          0x0031 },
    { AV_CODEC_ID_GSM_MS,          0x0032 },  /* msn audio */
    { AV_CODEC_ID_AMR_NB,          0x0038 },  /* rogue format number */
    { AV_CODEC_ID_G723_1,          0x0042 },
    { AV_CODEC_ID_ADPCM_G726,      0x0045 },
    { AV_CODEC_ID_ADPCM_G726,      0x0014 },  /* g723 Antex */
    { AV_CODEC_ID_ADPCM_G726,      0x0040 },  /* g721 Antex */
    { AV_CODEC_ID_MP2,             0x0050 },
    { AV_CODEC_ID_MP3,             0x0055 },
    { AV_CODEC_ID_AMR_NB,          0x0057 },
    { AV_CODEC_ID_AMR_WB,          0x0058 },
    /* rogue format number */
    { AV_CODEC_ID_ADPCM_IMA_DK4,   0x0061 },
    /* rogue format number */
    { AV_CODEC_ID_ADPCM_IMA_DK3,   0x0062 },
    { AV_CODEC_ID_ADPCM_G726,      0x0064 },
    { AV_CODEC_ID_ADPCM_IMA_WAV,   0x0069 },
    { AV_CODEC_ID_METASOUND,       0x0075 },
    { AV_CODEC_ID_G729,            0x0083 },
    { AV_CODEC_ID_AAC,             0x00ff },
    { AV_CODEC_ID_G723_1,          0x0111 },
    { AV_CODEC_ID_SIPR,            0x0130 },
    { AV_CODEC_ID_WMAV1,           0x0160 },
    { AV_CODEC_ID_WMAV2,           0x0161 },
    { AV_CODEC_ID_WMAPRO,          0x0162 },
    { AV_CODEC_ID_WMALOSSLESS,     0x0163 },
    { AV_CODEC_ID_XMA1,            0x0165 },
    { AV_CODEC_ID_XMA2,            0x0166 },
    { AV_CODEC_ID_ADPCM_CT,        0x0200 },
    { AV_CODEC_ID_DVAUDIO,         0x0215 },
    { AV_CODEC_ID_DVAUDIO,         0x0216 },
    { AV_CODEC_ID_ATRAC3,          0x0270 },
    { AV_CODEC_ID_ADPCM_G722,      0x028F },
    { AV_CODEC_ID_IMC,             0x0401 },
    { AV_CODEC_ID_IAC,             0x0402 },
    { AV_CODEC_ID_ON2AVC,          0x0500 },
    { AV_CODEC_ID_ON2AVC,          0x0501 },
    { AV_CODEC_ID_GSM_MS,          0x1500 },
    { AV_CODEC_ID_TRUESPEECH,      0x1501 },
    /* ADTS AAC */
    { AV_CODEC_ID_AAC,             0x1600 },
    { AV_CODEC_ID_AAC_LATM,        0x1602 },
    { AV_CODEC_ID_AC3,             0x2000 },
    /* There is no Microsoft Format Tag for E-AC3, the GUID has to be used */
    { AV_CODEC_ID_EAC3,            0x2000 },
    { AV_CODEC_ID_DTS,             0x2001 },
    { AV_CODEC_ID_SONIC,           0x2048 },
    { AV_CODEC_ID_SONIC_LS,        0x2048 },
    { AV_CODEC_ID_PCM_MULAW,       0x6c75 },
    { AV_CODEC_ID_AAC,             0x706d },
    { AV_CODEC_ID_AAC,             0x4143 },
    { AV_CODEC_ID_XAN_DPCM,        0x594a },
    { AV_CODEC_ID_G729,            0x729A },
    { AV_CODEC_ID_G723_1,          0xA100 }, /* Comverse Infosys Ltd. G723 1 */
    { AV_CODEC_ID_AAC,             0xA106 },
    { AV_CODEC_ID_SPEEX,           0xA109 },
    { AV_CODEC_ID_FLAC,            0xF1AC },
    { AV_CODEC_ID_ADPCM_SWF,       ('S' << 8) + 'F' },
    /* HACK/FIXME: Does Vorbis in WAV/AVI have an (in)official ID? */
    { AV_CODEC_ID_VORBIS,          ('V' << 8) + 'o' },
    { AV_CODEC_ID_NONE,      0 },
}

其中我們可以找到AV_CODEC_ID_ADPCM_G726，但是沒有AV_CODEC_ID_ADPCM_G726LE。

其中RIFF Tag可參考：https://sno.phy.queensu.ca/~phil/exiftool/TagNames/RIFF.html