[Libav-user] sample_fmt_entry

[Liang Zhang]

Hello,

I tested the example program of demuxing for decoding audio signals and
have received the information regarding "unsupported audio format for ftlp"
when the input data has the extension of mp4. I checked the program and
found that the example function (int get_format_from_sample_fmt ) only
declare the sample format as follows:

   struct sample_fmt_entry {
        enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
    } sample_fmt_entries[] = {
        { AV_SAMPLE_FMT_U8,  "u8",    "u8"    },
        { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
        { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
        { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
        { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
}

However, ffmpeg also support other  sample type that I listed as follows:

        { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
        { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
        { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
        { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
        { AV_SAMPLE_FMT_U8P, "?", "?" },
        { AV_SAMPLE_FMT_S16P,  "?", "?" },
        { AV_SAMPLE_FMT_S32P,  "?", "?" },
        { AV_SAMPLE_FMT_FLTP, "?", "?" },
        { AV_SAMPLE_FMT_DBLP, "?", "?" },
        { AV_SAMPLE_FMT_NB, "?", "?" },

To extend the sample_fmt_entries[] in the function (int
get_format_from_sample_fmt ) to include other sample ypes,
what should I fill in for the items of fmt_be and fmt_le as indicated using
question marks?

As my understand, the information fmt_be and fmt_le are needed for ffplay
command line to replay the decoded audio samples.

Thanks for the help in advance,

Liang
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