1 /*
2 * Copyright (c) 2010 Nicolas George
3 * Copyright (c) 2011 Stefano Sabatini
4 * Copyright (c) 2012 Clément Bœsch
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 /**
26 * @file
27 * API example for audio decoding and filtering
28 * @example filtering_audio.c
29 */
30
31 #include <unistd.h>
32
33 #include <libavcodec/avcodec.h>
34 #include <libavformat/avformat.h>
35 #include <libavfilter/buffersink.h>
36 #include <libavfilter/buffersrc.h>
37 #include <libavutil/opt.h>
38
39 static const char *filter_descr = "aresample=8000,aformat=sample_fmts=s16:channel_layouts=mono";
40 static const char *player = "ffplay -f s16le -ar 8000 -ac 1 -";
41
42 static AVFormatContext *fmt_ctx;
43 static AVCodecContext *dec_ctx;
44 AVFilterContext *buffersink_ctx;
45 AVFilterContext *buffersrc_ctx;
46 AVFilterGraph *filter_graph;
47 static int audio_stream_index = -1;
48
open_input_file(const char * filename)49 static int open_input_file(const char *filename)
50 {
51 int ret;
52 AVCodec *dec;
53
54 if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
55 av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
56 return ret;
57 }
58
59 if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
60 av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
61 return ret;
62 }
63
64 /* select the audio stream */
65 ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, &dec, 0);
66 if (ret < 0) {
67 av_log(NULL, AV_LOG_ERROR, "Cannot find an audio stream in the input file\n");
68 return ret;
69 }
70 audio_stream_index = ret;
71
72 /* create decoding context */
73 dec_ctx = avcodec_alloc_context3(dec);
74 if (!dec_ctx)
75 return AVERROR(ENOMEM);
76 avcodec_parameters_to_context(dec_ctx, fmt_ctx->streams[audio_stream_index]->codecpar);
77
78 /* init the audio decoder */
79 if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
80 av_log(NULL, AV_LOG_ERROR, "Cannot open audio decoder\n");
81 return ret;
82 }
83
84 return 0;
85 }
86
init_filters(const char * filters_descr)87 static int init_filters(const char *filters_descr)
88 {
89 char args[512];
90 int ret = 0;
91 const AVFilter *abuffersrc = avfilter_get_by_name("abuffer");
92 const AVFilter *abuffersink = avfilter_get_by_name("abuffersink");
93 AVFilterInOut *outputs = avfilter_inout_alloc();
94 AVFilterInOut *inputs = avfilter_inout_alloc();
95 static const enum AVSampleFormat out_sample_fmts[] = { AV_SAMPLE_FMT_S16, -1 };
96 static const int64_t out_channel_layouts[] = { AV_CH_LAYOUT_MONO, -1 };
97 static const int out_sample_rates[] = { 8000, -1 };
98 const AVFilterLink *outlink;
99 AVRational time_base = fmt_ctx->streams[audio_stream_index]->time_base;
100
101 filter_graph = avfilter_graph_alloc();
102 if (!outputs || !inputs || !filter_graph) {
103 ret = AVERROR(ENOMEM);
104 goto end;
105 }
106
107 /* buffer audio source: the decoded frames from the decoder will be inserted here. */
108 if (!dec_ctx->channel_layout)
109 dec_ctx->channel_layout = av_get_default_channel_layout(dec_ctx->channels);
110 snprintf(args, sizeof(args),
111 "time_base=%d/%d:sample_rate=%d:sample_fmt=%s:channel_layout=0x%"PRIx64,
112 time_base.num, time_base.den, dec_ctx->sample_rate,
113 av_get_sample_fmt_name(dec_ctx->sample_fmt), dec_ctx->channel_layout);
114 ret = avfilter_graph_create_filter(&buffersrc_ctx, abuffersrc, "in",
115 args, NULL, filter_graph);
116 if (ret < 0) {
117 av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer source\n");
118 goto end;
119 }
120
121 /* buffer audio sink: to terminate the filter chain. */
122 ret = avfilter_graph_create_filter(&buffersink_ctx, abuffersink, "out",
123 NULL, NULL, filter_graph);
124 if (ret < 0) {
125 av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer sink\n");
126 goto end;
127 }
128
129 ret = av_opt_set_int_list(buffersink_ctx, "sample_fmts", out_sample_fmts, -1,
130 AV_OPT_SEARCH_CHILDREN);
131 if (ret < 0) {
132 av_log(NULL, AV_LOG_ERROR, "Cannot set output sample format\n");
133 goto end;
134 }
135
136 ret = av_opt_set_int_list(buffersink_ctx, "channel_layouts", out_channel_layouts, -1,
137 AV_OPT_SEARCH_CHILDREN);
138 if (ret < 0) {
139 av_log(NULL, AV_LOG_ERROR, "Cannot set output channel layout\n");
140 goto end;
141 }
142
143 ret = av_opt_set_int_list(buffersink_ctx, "sample_rates", out_sample_rates, -1,
144 AV_OPT_SEARCH_CHILDREN);
145 if (ret < 0) {
146 av_log(NULL, AV_LOG_ERROR, "Cannot set output sample rate\n");
147 goto end;
148 }
149
150 /*
151 * Set the endpoints for the filter graph. The filter_graph will
152 * be linked to the graph described by filters_descr.
153 */
154
155 /*
156 * The buffer source output must be connected to the input pad of
157 * the first filter described by filters_descr; since the first
158 * filter input label is not specified, it is set to "in" by
159 * default.
160 */
161 outputs->name = av_strdup("in");
162 outputs->filter_ctx = buffersrc_ctx;
163 outputs->pad_idx = 0;
164 outputs->next = NULL;
165
166 /*
167 * The buffer sink input must be connected to the output pad of
168 * the last filter described by filters_descr; since the last
169 * filter output label is not specified, it is set to "out" by
170 * default.
171 */
172 inputs->name = av_strdup("out");
173 inputs->filter_ctx = buffersink_ctx;
174 inputs->pad_idx = 0;
175 inputs->next = NULL;
176
177 if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
178 &inputs, &outputs, NULL)) < 0)
179 goto end;
180
181 if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
182 goto end;
183
184 /* Print summary of the sink buffer
185 * Note: args buffer is reused to store channel layout string */
186 outlink = buffersink_ctx->inputs[0];
187 av_get_channel_layout_string(args, sizeof(args), -1, outlink->channel_layout);
188 av_log(NULL, AV_LOG_INFO, "Output: srate:%dHz fmt:%s chlayout:%s\n",
189 (int)outlink->sample_rate,
190 (char *)av_x_if_null(av_get_sample_fmt_name(outlink->format), "?"),
191 args);
192
193 end:
194 avfilter_inout_free(&inputs);
195 avfilter_inout_free(&outputs);
196
197 return ret;
198 }
199
print_frame(const AVFrame * frame)200 static void print_frame(const AVFrame *frame)
201 {
202 const int n = frame->nb_samples * av_get_channel_layout_nb_channels(frame->channel_layout);
203 const uint16_t *p = (uint16_t*)frame->data[0];
204 const uint16_t *p_end = p + n;
205
206 while (p < p_end) {
207 fputc(*p & 0xff, stdout);
208 fputc(*p>>8 & 0xff, stdout);
209 p++;
210 }
211 fflush(stdout);
212 }
213
main(int argc,char ** argv)214 int main(int argc, char **argv)
215 {
216 int ret;
217 AVPacket packet;
218 AVFrame *frame = av_frame_alloc();
219 AVFrame *filt_frame = av_frame_alloc();
220
221 if (!frame || !filt_frame) {
222 perror("Could not allocate frame");
223 exit(1);
224 }
225 if (argc != 2) {
226 fprintf(stderr, "Usage: %s file | %s\n", argv[0], player);
227 exit(1);
228 }
229
230 if ((ret = open_input_file(argv[1])) < 0)
231 goto end;
232 if ((ret = init_filters(filter_descr)) < 0)
233 goto end;
234
235 /* read all packets */
236 while (1) {
237 if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
238 break;
239
240 if (packet.stream_index == audio_stream_index) {
241 ret = avcodec_send_packet(dec_ctx, &packet);
242 if (ret < 0) {
243 av_log(NULL, AV_LOG_ERROR, "Error while sending a packet to the decoder\n");
244 break;
245 }
246
247 while (ret >= 0) {
248 ret = avcodec_receive_frame(dec_ctx, frame);
249 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
250 break;
251 } else if (ret < 0) {
252 av_log(NULL, AV_LOG_ERROR, "Error while receiving a frame from the decoder\n");
253 goto end;
254 }
255
256 if (ret >= 0) {
257 /* push the audio data from decoded frame into the filtergraph */
258 if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
259 av_log(NULL, AV_LOG_ERROR, "Error while feeding the audio filtergraph\n");
260 break;
261 }
262
263 /* pull filtered audio from the filtergraph */
264 while (1) {
265 ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
266 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
267 break;
268 if (ret < 0)
269 goto end;
270 print_frame(filt_frame);
271 av_frame_unref(filt_frame);
272 }
273 av_frame_unref(frame);
274 }
275 }
276 }
277 av_packet_unref(&packet);
278 }
279 end:
280 avfilter_graph_free(&filter_graph);
281 avcodec_free_context(&dec_ctx);
282 avformat_close_input(&fmt_ctx);
283 av_frame_free(&frame);
284 av_frame_free(&filt_frame);
285
286 if (ret < 0 && ret != AVERROR_EOF) {
287 fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
288 exit(1);
289 }
290
291 exit(0);
292 }
293