打开PCM设备 设置硬件参数 读/写数据 PCM播放示例代码 PCM录音示例代码 使用异步方法 snd_async_add_pcm_handler()函数 snd_pcm_avail_update()函数 PCM异步播放示例 PCM异步录音示例 使用poll()函数 使用poll I/O多路复用实现读写 PCM播放示例 PCM录音示例 PCM设备状态 PCM播放——加入状态控制 snd_pcm_readi/...
您可以使用snd_pcm_rewind()删除挂起的帧。通常情况下，回退允许您使用较大的周期缓冲区，同时仍然能够...
voidalsa_pause(struct codec *c,intp){structalsa_state*state= (structalsa_state*)c->data;if(snd_pcm_state(state->dev) != SND_PCM_STATE_PAUSED)snd_pcm_delay(state->dev, &state->delay); snd_pcm_pause(state->dev, p); } 开发者ID:kernelOfTruth,项目名称:dsp,代码行数:7,代码来源:alsa...
uint period_time = settings.value("period_time",100).toUInt()*1000;booluse_pause = settings.value("use_snd_pcm_pause",false).toBool(); settings.endGroup();snd_pcm_hw_params_t*hwparams =0;snd_pcm_sw_params_t*swparams =0;interr;//alsa error code//hw paramssnd_pcm_hw_params_allo...
本文主要详细分析snd_pcm_open。snd_pcm_open顺序图代码详细分析 (以播放为例)问题引入alsa_utils aplay.c 中的播放接口采用函数指针实现,具体定义如下static snd_pcm_sframes_t (*writei_func)(snd_pcm_t *handle, const void *buffer, snd_pcm_uframes_t size);登录后复制赋值如下 writei_func = snd_...
PCM全称Pulse-Code Modulation,就是脉冲调制编码,简单来说就是一种用数字表示采样模拟信号的方法。 从声卡设备生成PCM数据需要三个阶段:采样、量化、编码,关于这三者的细节不多说,我们直接看下PCM的格式: 例如一段有符号的 8-bit 的 pcm 数据: +---+---+---+--- binary | 0010 0000 | 1010 0000 |...
This adds a virtio based sound card device that provides output and input PCM streams to a virtual guest. In order to build the virtio-snd device the VIRTIO_SND configuration option should be enabled in the hw/audio/Kconfig file. The device can be provided to a guest using the following ...
(31 Steps) – Bass Boost Sound Effect – Ancillary Data Extraction – CRC Error and MPEG Frame Synchronization Indicators • Programmable Audio Output for Interfacing with Common Audio DAC Single-Chip – PCM Format Compatible 2 – I S Format Compatible Flash • 8-bit MCU C51 Core Based (...
uint period_time = settings.value("period_time",100).toUInt()*1000;booluse_pause = settings.value("use_snd_pcm_pause",false).toBool(); settings.endGroup();snd_pcm_hw_params_t*hwparams =0;snd_pcm_sw_params_t*swparams =0;interr;//alsa error code//hw paramssnd_pcm_hw_params_allo...
period_time=125000;snd_pcm_hw_params_set_period_time_near(handle, params,&period_time,0); buffer_time =500000; snd_pcm_hw_params_set_buffer_time_near(handle, params, &buffer_time,0);/*monotonic = */snd_pcm_hw_params_is_monotonic(params);/*can_pause = */snd_pcm_hw_params_can_...