From aecf0cf5ed907993d41009c6f2a7aa7c3904b837 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Cl=C3=A9ment=20B=C5=93sch?= Date: Mon, 20 Feb 2012 13:49:18 +0100 Subject: [PATCH] doc/examples: add audio decoding/filtering example. Mostly based on doc/examples/filtering.c. lavfi API is still limited to "buffer feeding" instead of "frame feeding" at the moment, so this example code sticks with it. --- doc/examples/Makefile | 2 +- doc/examples/filtering_audio.c | 245 +++++++++++++++++++++++++++++++++ 2 files changed, 246 insertions(+), 1 deletion(-) create mode 100644 doc/examples/filtering_audio.c diff --git a/doc/examples/Makefile b/doc/examples/Makefile index b4d299ff67..6b9902df6e 100644 --- a/doc/examples/Makefile +++ b/doc/examples/Makefile @@ -3,7 +3,7 @@ FFMPEG_LIBS=libavdevice libavformat libavfilter libavcodec libswscale libavutil CFLAGS+=-Wall $(shell pkg-config --cflags $(FFMPEG_LIBS)) LDFLAGS+=$(shell pkg-config --libs $(FFMPEG_LIBS)) -EXAMPLES=decoding_encoding filtering metadata muxing +EXAMPLES=decoding_encoding filtering filtering_audio metadata muxing OBJS=$(addsuffix .o,$(EXAMPLES)) diff --git a/doc/examples/filtering_audio.c b/doc/examples/filtering_audio.c new file mode 100644 index 0000000000..988dbfe3c2 --- /dev/null +++ b/doc/examples/filtering_audio.c @@ -0,0 +1,245 @@ +/* + * Copyright (c) 2010 Nicolas George + * Copyright (c) 2011 Stefano Sabatini + * Copyright (c) 2012 Clément Bœsch + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +/** + * @file + * API example for audio decoding and filtering + */ + +#include + +#include +#include +#include +#include +#include +#include + +const char *filter_descr = "aresample=8000,aconvert=s16:mono"; +const char *player = "ffplay -f s16le -ar 8000 -ac 1 -"; + +static AVFormatContext *fmt_ctx; +static AVCodecContext *dec_ctx; +AVFilterContext *buffersink_ctx; +AVFilterContext *buffersrc_ctx; +AVFilterGraph *filter_graph; +static int audio_stream_index = -1; + +static int open_input_file(const char *filename) +{ + int ret; + AVCodec *dec; + + if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) { + av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n"); + return ret; + } + + if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) { + av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n"); + return ret; + } + + /* select the audio stream */ + ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, &dec, 0); + if (ret < 0) { + av_log(NULL, AV_LOG_ERROR, "Cannot find a audio stream in the input file\n"); + return ret; + } + audio_stream_index = ret; + dec_ctx = fmt_ctx->streams[audio_stream_index]->codec; + + /* init the audio decoder */ + if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) { + av_log(NULL, AV_LOG_ERROR, "Cannot open audio decoder\n"); + return ret; + } + + return 0; +} + +static int init_filters(const char *filters_descr) +{ + char args[512]; + int ret; + AVFilter *abuffersrc = avfilter_get_by_name("abuffer"); + AVFilter *abuffersink = avfilter_get_by_name("abuffersink"); + AVFilterInOut *outputs = avfilter_inout_alloc(); + AVFilterInOut *inputs = avfilter_inout_alloc(); + const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16, -1 }; + const int packing_fmts[] = { AVFILTER_PACKED, -1 }; + const int64_t *chlayouts = avfilter_all_channel_layouts; + AVABufferSinkParams *abuffersink_params; + const AVFilterLink *outlink; + + filter_graph = avfilter_graph_alloc(); + + /* buffer audio source: the decoded frames from the decoder will be inserted here. */ + if (!dec_ctx->channel_layout) + dec_ctx->channel_layout = av_get_default_channel_layout(dec_ctx->channels); + snprintf(args, sizeof(args), "%d:%d:0x%"PRIx64":packed", + dec_ctx->sample_rate, dec_ctx->sample_fmt, dec_ctx->channel_layout); + ret = avfilter_graph_create_filter(&buffersrc_ctx, abuffersrc, "in", + args, NULL, filter_graph); + if (ret < 0) { + av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer source\n"); + return ret; + } + + /* buffer audio sink: to terminate the filter chain. */ + abuffersink_params = av_abuffersink_params_alloc(); + abuffersink_params->sample_fmts = sample_fmts; + abuffersink_params->channel_layouts = chlayouts; + abuffersink_params->packing_fmts = packing_fmts; + ret = avfilter_graph_create_filter(&buffersink_ctx, abuffersink, "out", + NULL, abuffersink_params, filter_graph); + if (ret < 0) { + av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer sink\n"); + return ret; + } + + /* Endpoints for the filter graph. */ + outputs->name = av_strdup("in"); + outputs->filter_ctx = buffersrc_ctx; + outputs->pad_idx = 0; + outputs->next = NULL; + + inputs->name = av_strdup("out"); + inputs->filter_ctx = buffersink_ctx; + inputs->pad_idx = 0; + inputs->next = NULL; + + if ((ret = avfilter_graph_parse(filter_graph, filter_descr, + &inputs, &outputs, NULL)) < 0) + return ret; + + if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0) + return ret; + + /* Print summary of the sink buffer + * Note: args buffer is reused to store channel layout string */ + outlink = buffersink_ctx->inputs[0]; + av_get_channel_layout_string(args, sizeof(args), -1, outlink->channel_layout); + av_log(NULL, AV_LOG_INFO, "Output: srate:%dHz fmt:%s chlayout:%s\n", + (int)outlink->sample_rate, + (char *)av_x_if_null(av_get_sample_fmt_name(outlink->format), "?"), + args); + + return 0; +} + +static void print_samplesref(AVFilterBufferRef *samplesref) +{ + const AVFilterBufferRefAudioProps *props = samplesref->audio; + const int n = props->nb_samples * av_get_channel_layout_nb_channels(props->channel_layout); + const uint16_t *p = (uint16_t*)samplesref->data[0]; + const uint16_t *p_end = p + n; + + while (p < p_end) { + fputc(*p & 0xff, stdout); + fputc(*p>>8 & 0xff, stdout); + p++; + } + fflush(stdout); +} + +int main(int argc, char **argv) +{ + int ret; + AVPacket packet; + AVFrame frame; + int got_frame; + + if (argc != 2) { + fprintf(stderr, "Usage: %s file | %s\n", argv[0], player); + exit(1); + } + + avcodec_register_all(); + av_register_all(); + avfilter_register_all(); + + if ((ret = open_input_file(argv[1])) < 0) + goto end; + if ((ret = init_filters(filter_descr)) < 0) + goto end; + + /* read all packets */ + while (1) { + AVFilterBufferRef *samplesref; + if ((ret = av_read_frame(fmt_ctx, &packet)) < 0) + break; + + if (packet.stream_index == audio_stream_index) { + avcodec_get_frame_defaults(&frame); + got_frame = 0; + ret = avcodec_decode_audio4(dec_ctx, &frame, &got_frame, &packet); + av_free_packet(&packet); + if (ret < 0) { + av_log(NULL, AV_LOG_ERROR, "Error decoding audio\n"); + break; + } + + if (got_frame) { + const int bps = av_get_bytes_per_sample(dec_ctx->sample_fmt); + const int decoded_data_size = frame.nb_samples * dec_ctx->channels * bps; + + /* push the audio data from decoded frame into the filtergraph */ + if (av_asrc_buffer_add_buffer(buffersrc_ctx, + frame.data[0], + decoded_data_size, + dec_ctx->sample_rate, + dec_ctx->sample_fmt, + dec_ctx->channel_layout, + 0, frame.pts, 0) < 0) { + av_log(NULL, AV_LOG_ERROR, "Error while feeding the audio filtergraph\n"); + break; + } + + /* pull filtered audio from the filtergraph */ + while (avfilter_poll_frame(buffersink_ctx->inputs[0])) { + av_buffersink_get_buffer_ref(buffersink_ctx, &samplesref, 0); + if (samplesref) { + print_samplesref(samplesref); + avfilter_unref_buffer(samplesref); + } + } + } + } + } +end: + avfilter_graph_free(&filter_graph); + if (dec_ctx) + avcodec_close(dec_ctx); + avformat_close_input(&fmt_ctx); + + if (ret < 0 && ret != AVERROR_EOF) { + char buf[1024]; + av_strerror(ret, buf, sizeof(buf)); + fprintf(stderr, "Error occurred: %s\n", buf); + exit(1); + } + + exit(0); +}