ffmpeg AV_SAMPLE_FMT_FLTP to AV_SAMPLE_FMT_S16

ffmpeg 2.0 音频解码出来的数据格式不符合Android音频格式 

问题原因：

ffmpeg2.0最新的解码出来的数据是 sample_fmts  = AV_SAMPLE_FMT_FLTP

android需要的音频格式：sample_fmts (AV_SAMPLE_FMT_S8, AV_SAMPLE_FMT_S16) 

解决方法：

1，  创建转换对象 

void audio_swr_resampling_audio_init(SwrContext **swr_ctx,TargetAudioParams *targetAudioParams,AVCodecContext *codec){

    if(codec->sample_fmt == AV_SAMPLE_FMT_S16 || codec->sample_fmt == AV_SAMPLE_FMT_S32 ||codec->sample_fmt == AV_SAMPLE_FMT_U8){

        LOGE("codec->sample_fmt:%d",codec->sample_fmt);

        if(*swr_ctx){

            swr_free(swr_ctx);

            *swr_ctx = NULL;

        }

        return;

    }

    if(*swr_ctx){

        swr_free(swr_ctx);

    }

    *swr_ctx = swr_alloc();

    if(!*swr_ctx){

        LOGE("swr_alloc failed");

        return;

    }

   

    /* set options */

    av_opt_set_int(*swr_ctx, "in_channel_layout",    codec->channel_layout, 0);

    av_opt_set_int(*swr_ctx, "in_sample_rate",       codec->sample_rate, 0);

    av_opt_set_sample_fmt(*swr_ctx, "in_sample_fmt", codec->sample_fmt, 0);

    av_opt_set_int(*swr_ctx, "out_channel_layout",    targetAudioParams->channel_layout, 0);

    av_opt_set_int(*swr_ctx, "out_sample_rate",       targetAudioParams->sample_rate, 0);

    av_opt_set_sample_fmt(*swr_ctx, "out_sample_fmt", targetAudioParams->sample_fmt, 0);// AV_SAMPLE_FMT_S16

    /* initialize the resampling context */

    int ret = 0;

    if ((ret = swr_init(*swr_ctx)) < 0) {

        LOGE("Failed to initialize the resampling context\n");

        if(*swr_ctx){

            swr_free(swr_ctx);

            *swr_ctx = NULL;

        }

        return;

    }

}

2，  转换(AV_SAMPLE_FMT_FLTP àAV_SAMPLE_FMT_S16) 

int audio_swr_resampling_audio(SwrContext *swr_ctx,TargetAudioParams *targetAudioParams,AVFrame *audioFrame,uint8_t **targetData){

    int len = swr_convert(swr_ctx,targetData,audioFrame->nb_samples,audioFrame->extended_data,audioFrame->nb_samples);

    if(len < 0){

        LOGE("error swr_convert");

        goto end;

    }

    int dst_bufsize = len * targetAudioParams->channels * av_get_bytes_per_sample(targetAudioParams->sample_fmt);

    LOGI(" dst_bufsize:%d",dst_bufsize);

    return dst_bufsize;

    end:

        return -1;

}

3，  销毁

最后处理完成销毁对象

void audio_swr_resampling_audio_destory(SwrContext **swr_ctx){

    if(*swr_ctx){

        swr_free(swr_ctx);

        *swr_ctx = NULL;

    }

}

参考：http://stackoverflow.com/questions/14989397/how-to-convert-sample-rate-from-av-sample-fmt-fltp-to-av-sample-fmt-s16