swr_alloc()数组
分配音频重采样的上下文函数
swr_alloc_set_opts(...)ui
设置音频重采样参数,能够经过音频的样本率来改变播放速度,但声音通常会失真spa
struct SwrContext *swr_alloc_set_opts(struct SwrContext *s, int64_t out_ch_layout, enum AVSampleFormat out_sample_fmt, int out_sample_rate, int64_t in_ch_layout, enum AVSampleFormat in_sample_fmt, int in_sample_rate, int log_offset, void *log_ctx);
参数说明:指针
swr_init(struct SwrContext *s)日志
初始化音频重采样上下文code
swr_convert(...)orm
对音频帧进行重采样blog
int swr_convert(struct SwrContext *s, uint8_t **out, int out_count, const uint8_t **in , int in_count);
参数说明:get
swr_free(struct SwrContext **s)
释放音频重采样上下文空间
//音频重采样上下文初始化 SwrContext *swrContext = swr_alloc(); char *pcm = new char[480000*4*2]; swrContext = swr_alloc_set_opts(swrContext, av_get_default_channel_layout(2), AV_SAMPLE_FMT_S16, ac->sample_rate, av_get_default_channel_layout(ac->channels), ac->sample_fmt, ac->sample_rate, 0, 0); re = swr_init(swrContext); if (re != 0) { LOGI("swr_init failed"); } else { LOGI("swr_init success"); }
uint8_t *out[2] = {0}; out[0] = (uint8_t *)pcm; //转换音频帧 int len = swr_convert(swrContext, out, frame->nb_samples, (const uint8_t **)frame->data, frame->nb_samples);
注意:
音频重采样的相关函数包含在 libswresample.so 库中
同时在代码中包含头文件 #include <libswresample/swresample.h>