2 * Copyright (c) 2010 Nicolas George
3 * Copyright (c) 2011 Stefano Sabatini
4 * Copyright (c) 2012 Clément Bœsch
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:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
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
27 * API example for audio decoding and filtering
28 * @example filtering_audio.c
33 #include <libavcodec/avcodec.h>
34 #include <libavformat/avformat.h>
35 #include <libavfilter/avfiltergraph.h>
36 #include <libavfilter/avcodec.h>
37 #include <libavfilter/buffersink.h>
38 #include <libavfilter/buffersrc.h>
39 #include <libavutil/opt.h>
41 static const char *filter_descr
= "aresample=8000,aformat=sample_fmts=s16:channel_layouts=mono";
42 static const char *player
= "ffplay -f s16le -ar 8000 -ac 1 -";
44 static AVFormatContext
*fmt_ctx
;
45 static AVCodecContext
*dec_ctx
;
46 AVFilterContext
*buffersink_ctx
;
47 AVFilterContext
*buffersrc_ctx
;
48 AVFilterGraph
*filter_graph
;
49 static int audio_stream_index
= -1;
51 static int open_input_file(const char *filename
)
56 if ((ret
= avformat_open_input(&fmt_ctx
, filename
, NULL
, NULL
)) < 0) {
57 av_log(NULL
, AV_LOG_ERROR
, "Cannot open input file\n");
61 if ((ret
= avformat_find_stream_info(fmt_ctx
, NULL
)) < 0) {
62 av_log(NULL
, AV_LOG_ERROR
, "Cannot find stream information\n");
66 /* select the audio stream */
67 ret
= av_find_best_stream(fmt_ctx
, AVMEDIA_TYPE_AUDIO
, -1, -1, &dec
, 0);
69 av_log(NULL
, AV_LOG_ERROR
, "Cannot find a audio stream in the input file\n");
72 audio_stream_index
= ret
;
73 dec_ctx
= fmt_ctx
->streams
[audio_stream_index
]->codec
;
74 av_opt_set_int(dec_ctx
, "refcounted_frames", 1, 0);
76 /* init the audio decoder */
77 if ((ret
= avcodec_open2(dec_ctx
, dec
, NULL
)) < 0) {
78 av_log(NULL
, AV_LOG_ERROR
, "Cannot open audio decoder\n");
85 static int init_filters(const char *filters_descr
)
89 AVFilter
*abuffersrc
= avfilter_get_by_name("abuffer");
90 AVFilter
*abuffersink
= avfilter_get_by_name("abuffersink");
91 AVFilterInOut
*outputs
= avfilter_inout_alloc();
92 AVFilterInOut
*inputs
= avfilter_inout_alloc();
93 static const enum AVSampleFormat out_sample_fmts
[] = { AV_SAMPLE_FMT_S16
, -1 };
94 static const int64_t out_channel_layouts
[] = { AV_CH_LAYOUT_MONO
, -1 };
95 static const int out_sample_rates
[] = { 8000, -1 };
96 const AVFilterLink
*outlink
;
97 AVRational time_base
= fmt_ctx
->streams
[audio_stream_index
]->time_base
;
99 filter_graph
= avfilter_graph_alloc();
100 if (!outputs
|| !inputs
|| !filter_graph
) {
101 ret
= AVERROR(ENOMEM
);
105 /* buffer audio source: the decoded frames from the decoder will be inserted here. */
106 if (!dec_ctx
->channel_layout
)
107 dec_ctx
->channel_layout
= av_get_default_channel_layout(dec_ctx
->channels
);
108 snprintf(args
, sizeof(args
),
109 "time_base=%d/%d:sample_rate=%d:sample_fmt=%s:channel_layout=0x%"PRIx64
,
110 time_base
.num
, time_base
.den
, dec_ctx
->sample_rate
,
111 av_get_sample_fmt_name(dec_ctx
->sample_fmt
), dec_ctx
->channel_layout
);
112 ret
= avfilter_graph_create_filter(&buffersrc_ctx
, abuffersrc
, "in",
113 args
, NULL
, filter_graph
);
115 av_log(NULL
, AV_LOG_ERROR
, "Cannot create audio buffer source\n");
119 /* buffer audio sink: to terminate the filter chain. */
120 ret
= avfilter_graph_create_filter(&buffersink_ctx
, abuffersink
, "out",
121 NULL
, NULL
, filter_graph
);
123 av_log(NULL
, AV_LOG_ERROR
, "Cannot create audio buffer sink\n");
127 ret
= av_opt_set_int_list(buffersink_ctx
, "sample_fmts", out_sample_fmts
, -1,
128 AV_OPT_SEARCH_CHILDREN
);
130 av_log(NULL
, AV_LOG_ERROR
, "Cannot set output sample format\n");
134 ret
= av_opt_set_int_list(buffersink_ctx
, "channel_layouts", out_channel_layouts
, -1,
135 AV_OPT_SEARCH_CHILDREN
);
137 av_log(NULL
, AV_LOG_ERROR
, "Cannot set output channel layout\n");
141 ret
= av_opt_set_int_list(buffersink_ctx
, "sample_rates", out_sample_rates
, -1,
142 AV_OPT_SEARCH_CHILDREN
);
144 av_log(NULL
, AV_LOG_ERROR
, "Cannot set output sample rate\n");
148 /* Endpoints for the filter graph. */
149 outputs
->name
= av_strdup("in");
150 outputs
->filter_ctx
= buffersrc_ctx
;
151 outputs
->pad_idx
= 0;
152 outputs
->next
= NULL
;
154 inputs
->name
= av_strdup("out");
155 inputs
->filter_ctx
= buffersink_ctx
;
159 if ((ret
= avfilter_graph_parse_ptr(filter_graph
, filters_descr
,
160 &inputs
, &outputs
, NULL
)) < 0)
163 if ((ret
= avfilter_graph_config(filter_graph
, NULL
)) < 0)
166 /* Print summary of the sink buffer
167 * Note: args buffer is reused to store channel layout string */
168 outlink
= buffersink_ctx
->inputs
[0];
169 av_get_channel_layout_string(args
, sizeof(args
), -1, outlink
->channel_layout
);
170 av_log(NULL
, AV_LOG_INFO
, "Output: srate:%dHz fmt:%s chlayout:%s\n",
171 (int)outlink
->sample_rate
,
172 (char *)av_x_if_null(av_get_sample_fmt_name(outlink
->format
), "?"),
176 avfilter_inout_free(&inputs
);
177 avfilter_inout_free(&outputs
);
182 static void print_frame(const AVFrame
*frame
)
184 const int n
= frame
->nb_samples
* av_get_channel_layout_nb_channels(av_frame_get_channel_layout(frame
));
185 const uint16_t *p
= (uint16_t*)frame
->data
[0];
186 const uint16_t *p_end
= p
+ n
;
189 fputc(*p
& 0xff, stdout
);
190 fputc(*p
>>8 & 0xff, stdout
);
196 int main(int argc
, char **argv
)
199 AVPacket packet0
, packet
;
200 AVFrame
*frame
= av_frame_alloc();
201 AVFrame
*filt_frame
= av_frame_alloc();
204 if (!frame
|| !filt_frame
) {
205 perror("Could not allocate frame");
209 fprintf(stderr
, "Usage: %s file | %s\n", argv
[0], player
);
214 avfilter_register_all();
216 if ((ret
= open_input_file(argv
[1])) < 0)
218 if ((ret
= init_filters(filter_descr
)) < 0)
221 /* read all packets */
226 if ((ret
= av_read_frame(fmt_ctx
, &packet
)) < 0)
231 if (packet
.stream_index
== audio_stream_index
) {
233 ret
= avcodec_decode_audio4(dec_ctx
, frame
, &got_frame
, &packet
);
235 av_log(NULL
, AV_LOG_ERROR
, "Error decoding audio\n");
242 /* push the audio data from decoded frame into the filtergraph */
243 if (av_buffersrc_add_frame_flags(buffersrc_ctx
, frame
, 0) < 0) {
244 av_log(NULL
, AV_LOG_ERROR
, "Error while feeding the audio filtergraph\n");
248 /* pull filtered audio from the filtergraph */
250 ret
= av_buffersink_get_frame(buffersink_ctx
, filt_frame
);
251 if (ret
== AVERROR(EAGAIN
) || ret
== AVERROR_EOF
)
255 print_frame(filt_frame
);
256 av_frame_unref(filt_frame
);
260 if (packet
.size
<= 0)
261 av_free_packet(&packet0
);
263 /* discard non-wanted packets */
264 av_free_packet(&packet0
);
268 avfilter_graph_free(&filter_graph
);
269 avcodec_close(dec_ctx
);
270 avformat_close_input(&fmt_ctx
);
271 av_frame_free(&frame
);
272 av_frame_free(&filt_frame
);
274 if (ret
< 0 && ret
!= AVERROR_EOF
) {
275 fprintf(stderr
, "Error occurred: %s\n", av_err2str(ret
));