问题描述
我正在按照FFMpeg的官方教程创建过滤器链。 This 教程展示了如何通过链传递数据：
它使用的过滤器链是：*（输入）->abuffer->volume-> aformat -> abuffersink ->（输出）
这是我的代码 - 对不起，锅炉代码，这只是 ffmpeg 方式:(
frame = av_frame_alloc();
filtergraph = avfilter_graph_alloc();
if (!frame) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not allocate memory for frame");
return;
}
if (!filtergraph) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor FXProcessor! %s",av_err2str(AVERROR(ENOMEM)));
return;
}
const AVFilter *abuffer;
const AVFilter *abuffersink;
AVFilterContext *aformat_ctx;
const AVFilter *aformat;
AVFilterContext *choisen_beat_fx_ctx;
const AVFilter *choisen_beat_fx;
/* Create the abuffer filter;
* it will be used for Feeding the data into the graph. */
abuffer = avfilter_get_by_name("abuffer");
if (!abuffer) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not find the abuffer filter!");
return;
}
abuffer_ctx = avfilter_graph_alloc_filter(filtergraph,abuffer,"src");
if (!abuffer_ctx) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not allocate the abuffer_ctx instance! %s",av_err2str(AVERROR(ENOMEM)));
return;
}
char ch_layout[64];
/* Set the filter options through the AVOptions API. */
av_get_channel_layout_string(ch_layout,sizeof(ch_layout),AV_CH_LAYOUT_STEREO);
av_opt_set(abuffer_ctx,"channel_layout",ch_layout,AV_OPT_SEARCH_CHILDREN);
av_opt_set(abuffer_ctx,"sample_fmt",av_get_sample_fmt_name(AV_SAMPLE_FMT_FLT),AV_OPT_SEARCH_CHILDREN);
av_opt_set_q(abuffer_ctx,"time_base",(AVRational) {1,defaultSampleRate},AV_OPT_SEARCH_CHILDREN);
av_opt_set_int(abuffer_ctx,"sample_rate",defaultSampleRate,AV_OPT_SEARCH_CHILDREN);
/* Now initialize the filter; we pass NULL options,since we have already
* set all the options above. */
if (avfilter_init_str(abuffer_ctx,nullptr) < 0) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not initialize the abuffer filter!");
return;
}
// Todo: select FX's dynamically
/* Create aecho filter. */
if (true) {
choisen_beat_fx = avfilter_get_by_name("volume");
if (!choisen_beat_fx) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not find the aecho filter!");
return;
}
choisen_beat_fx_ctx = avfilter_graph_alloc_filter(filtergraph,choisen_beat_fx,"echo");
if (!choisen_beat_fx_ctx) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not allocate the choisen_beat_fx_ctx instance! %s",av_err2str(AVERROR(ENOMEM)));
return;
}
av_opt_set (choisen_beat_fx_ctx,"volume",AV_STRINGIFY(0.5),AV_OPT_SEARCH_CHILDREN);
if (avfilter_init_str(choisen_beat_fx_ctx,nullptr) < 0) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not initialize the choisen_beat_fx_ctx filter!");
return;
}
}
/* Create the aformat filter;
* it ensures that the output is of the format we want. */
aformat = avfilter_get_by_name("aformat");
if (!aformat) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not find the aformat filter!");
return;
}
aformat_ctx = avfilter_graph_alloc_filter(filtergraph,aformat,"aformat");
if (!aformat_ctx) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not allocate the aformat instance!");
return;
}
av_opt_set(aformat_ctx,"sample_fmts",AV_OPT_SEARCH_CHILDREN);
av_opt_set_int(aformat_ctx,"sample_rates",AV_OPT_SEARCH_CHILDREN);
av_get_channel_layout_string(ch_layout,AV_CH_LAYOUT_STEREO);
av_opt_set(aformat_ctx,"channel_layouts",AV_OPT_SEARCH_CHILDREN);
if (avfilter_init_str(aformat_ctx,nullptr) < 0) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not initialize the aformat filter!");
return;
}
/* Finally create the abuffersink filter;
* it will be used to get the filtered data out of the graph. */
abuffersink = avfilter_get_by_name("abuffersink");
if (!abuffersink) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not find the abuffersink filter!");
return;
}
abuffersink_ctx = avfilter_graph_alloc_filter(filtergraph,abuffersink,"sink");
if (!abuffersink_ctx) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not allocate the abuffersink instance!");
return;
}
/* This filter takes no options. */
if (avfilter_init_str(abuffersink_ctx,nullptr) < 0) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Could not initialize the abuffersink instance.!");
return;
}
/* Connect the filters;
* in this simple case the filters just form a linear chain. */
if (avfilter_link(abuffer_ctx,choisen_beat_fx_ctx,0) != 0) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Error connecting filters.!");
return;
}
if (avfilter_link(choisen_beat_fx_ctx,aformat_ctx,0) != 0) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Error connecting filters.!");
return;
}
if (avfilter_link(aformat_ctx,abuffersink_ctx,0) != 0) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Error connecting filters.!");
return;
}
/* Configure the graph. */
if (avfilter_graph_config(filtergraph,nullptr) < 0) {
*mediaLoadPointer = Failed_TO_LOAD;
LOGE("FXProcessor::FXProcessor Error configuring the filter graph!");
return;
}
当链是这个代码时工作正常
- (input) -> abuffer -> aecho-> aformat -> abuffersink -> (output)
但是，我想使用 adelay 而不是 volume 过滤器。所以我想要：
它使用的过滤器链是：*（输入）->abuffer->volume-> aformat -> abuffersink ->（输出）
我在
处更改了代码choisen_beat_fx = avfilter_get_by_name("volume");
到
choisen_beat_fx = avfilter_get_by_name("aecho");
并删除该行
av_opt_set (choisen_beat_fx_ctx,AV_OPT_SEARCH_CHILDREN);
一切都很顺利，直到最后一行。
avfilter_graph_config 失败并返回负值。函数文档：
avfilter_graph_config：检查有效性并配置所有链接和 图表中的格式。
所以我的猜测是我需要额外的链接来将 aecho 插入我的链？如何将 aecho 插入我的过滤器链？
解决方法
好的，问题是，我需要使用 aresample 过滤器进行编译才能使其正常工作。我重新编译，现在神奇地工作了。
这是我发现问题的方法。创建通用日志回调：
void ffmpegErrorCallback(void *ptr,int level,const char *fmt,va_list vargs) {
LOGE("ffmpegErrorCallback Error Occurred! Err: %s",fmt);
}
av_log_set_level(AV_LOG_ERROR);
av_log_set_callback(ffmpegErrorCallback);
FFmpeg 现在会将错误记录为人类可读的消息。它告诉我它找不到 aresample 过滤器。这就是我解决问题的方法。