1/*
2 * Copyright (c) 2012 Stefano Sabatini
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a copy
5 * of this software and associated documentation files (the "Software"), to deal
6 * in the Software without restriction, including without limitation the rights
7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 * copies of the Software, and to permit persons to whom the Software is
9 * furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20 * THE SOFTWARE.
21 */
22
23/**
24 * @file
25 * Demuxing and decoding example.
26 *
27 * Show how to use the libavformat and libavcodec API to demux and
28 * decode audio and video data.
29 * @example demuxing_decoding.c
30 */
31
32#include <libavutil/imgutils.h>
33#include <libavutil/samplefmt.h>
34#include <libavutil/timestamp.h>
35#include <libavcodec/avcodec.h>
36#include <libavformat/avformat.h>
37
38static AVFormatContext *fmt_ctx = NULL;
39static AVCodecContext *video_dec_ctx = NULL, *audio_dec_ctx;
40static int width, height;
41static enum AVPixelFormat pix_fmt;
42static AVStream *video_stream = NULL, *audio_stream = NULL;
43static const char *src_filename = NULL;
44static const char *video_dst_filename = NULL;
45static const char *audio_dst_filename = NULL;
46static FILE *video_dst_file = NULL;
47static FILE *audio_dst_file = NULL;
48
49static uint8_t *video_dst_data[4] = {NULL};
50static int      video_dst_linesize[4];
51static int video_dst_bufsize;
52
53static int video_stream_idx = -1, audio_stream_idx = -1;
54static AVFrame *frame = NULL;
55static AVPacket *pkt = NULL;
56static int video_frame_count = 0;
57static int audio_frame_count = 0;
58
59static int output_video_frame(AVFrame *frame)
60{
61    if (frame->width != width || frame->height != height ||
62        frame->format != pix_fmt) {
63        /* To handle this change, one could call av_image_alloc again and
64         * decode the following frames into another rawvideo file. */
65        fprintf(stderr, "Error: Width, height and pixel format have to be "
66                "constant in a rawvideo file, but the width, height or "
67                "pixel format of the input video changed:\n"
68                "old: width = %d, height = %d, format = %s\n"
69                "new: width = %d, height = %d, format = %s\n",
70                width, height, av_get_pix_fmt_name(pix_fmt),
71                frame->width, frame->height,
72                av_get_pix_fmt_name(frame->format));
73        return -1;
74    }
75
76    printf("video_frame n:%d coded_n:%d\n",
77           video_frame_count++, frame->coded_picture_number);
78
79    /* copy decoded frame to destination buffer:
80     * this is required since rawvideo expects non aligned data */
81    av_image_copy(video_dst_data, video_dst_linesize,
82                  (const uint8_t **)(frame->data), frame->linesize,
83                  pix_fmt, width, height);
84
85    /* write to rawvideo file */
86    fwrite(video_dst_data[0], 1, video_dst_bufsize, video_dst_file);
87    return 0;
88}
89
90static int output_audio_frame(AVFrame *frame)
91{
92    size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format);
93    printf("audio_frame n:%d nb_samples:%d pts:%s\n",
94           audio_frame_count++, frame->nb_samples,
95           av_ts2timestr(frame->pts, &audio_dec_ctx->time_base));
96
97    /* Write the raw audio data samples of the first plane. This works
98     * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However,
99     * most audio decoders output planar audio, which uses a separate
100     * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P).
101     * In other words, this code will write only the first audio channel
102     * in these cases.
103     * You should use libswresample or libavfilter to convert the frame
104     * to packed data. */
105    fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file);
106
107    return 0;
108}
109
110static int decode_packet(AVCodecContext *dec, const AVPacket *pkt)
111{
112    int ret = 0;
113
114    // submit the packet to the decoder
115    ret = avcodec_send_packet(dec, pkt);
116    if (ret < 0) {
117        fprintf(stderr, "Error submitting a packet for decoding (%s)\n", av_err2str(ret));
118        return ret;
119    }
120
121    // get all the available frames from the decoder
122    while (ret >= 0) {
123        ret = avcodec_receive_frame(dec, frame);
124        if (ret < 0) {
125            // those two return values are special and mean there is no output
126            // frame available, but there were no errors during decoding
127            if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN))
128                return 0;
129
130            fprintf(stderr, "Error during decoding (%s)\n", av_err2str(ret));
131            return ret;
132        }
133
134        // write the frame data to output file
135        if (dec->codec->type == AVMEDIA_TYPE_VIDEO)
136            ret = output_video_frame(frame);
137        else
138            ret = output_audio_frame(frame);
139
140        av_frame_unref(frame);
141        if (ret < 0)
142            return ret;
143    }
144
145    return 0;
146}
147
148static int open_codec_context(int *stream_idx,
149                              AVCodecContext **dec_ctx, AVFormatContext *fmt_ctx, enum AVMediaType type)
150{
151    int ret, stream_index;
152    AVStream *st;
153    const AVCodec *dec = NULL;
154
155    ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
156    if (ret < 0) {
157        fprintf(stderr, "Could not find %s stream in input file '%s'\n",
158                av_get_media_type_string(type), src_filename);
159        return ret;
160    } else {
161        stream_index = ret;
162        st = fmt_ctx->streams[stream_index];
163
164        /* find decoder for the stream */
165        dec = avcodec_find_decoder(st->codecpar->codec_id);
166        if (!dec) {
167            fprintf(stderr, "Failed to find %s codec\n",
168                    av_get_media_type_string(type));
169            return AVERROR(EINVAL);
170        }
171
172        /* Allocate a codec context for the decoder */
173        *dec_ctx = avcodec_alloc_context3(dec);
174        if (!*dec_ctx) {
175            fprintf(stderr, "Failed to allocate the %s codec context\n",
176                    av_get_media_type_string(type));
177            return AVERROR(ENOMEM);
178        }
179
180        /* Copy codec parameters from input stream to output codec context */
181        if ((ret = avcodec_parameters_to_context(*dec_ctx, st->codecpar)) < 0) {
182            fprintf(stderr, "Failed to copy %s codec parameters to decoder context\n",
183                    av_get_media_type_string(type));
184            return ret;
185        }
186
187        /* Init the decoders */
188        if ((ret = avcodec_open2(*dec_ctx, dec, NULL)) < 0) {
189            fprintf(stderr, "Failed to open %s codec\n",
190                    av_get_media_type_string(type));
191            return ret;
192        }
193        *stream_idx = stream_index;
194    }
195
196    return 0;
197}
198
199static int get_format_from_sample_fmt(const char **fmt,
200                                      enum AVSampleFormat sample_fmt)
201{
202    int i;
203    struct sample_fmt_entry {
204        enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
205    } sample_fmt_entries[] = {
206        { AV_SAMPLE_FMT_U8,  "u8",    "u8"    },
207        { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
208        { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
209        { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
210        { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
211    };
212    *fmt = NULL;
213
214    for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
215        struct sample_fmt_entry *entry = &sample_fmt_entries[i];
216        if (sample_fmt == entry->sample_fmt) {
217            *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
218            return 0;
219        }
220    }
221
222    fprintf(stderr,
223            "sample format %s is not supported as output format\n",
224            av_get_sample_fmt_name(sample_fmt));
225    return -1;
226}
227
228int main (int argc, char **argv)
229{
230    int ret = 0;
231
232    if (argc != 4) {
233        fprintf(stderr, "usage: %s  input_file video_output_file audio_output_file\n"
234                "API example program to show how to read frames from an input file.\n"
235                "This program reads frames from a file, decodes them, and writes decoded\n"
236                "video frames to a rawvideo file named video_output_file, and decoded\n"
237                "audio frames to a rawaudio file named audio_output_file.\n",
238                argv[0]);
239        exit(1);
240    }
241    src_filename = argv[1];
242    video_dst_filename = argv[2];
243    audio_dst_filename = argv[3];
244
245    /* open input file, and allocate format context */
246    if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
247        fprintf(stderr, "Could not open source file %s\n", src_filename);
248        exit(1);
249    }
250
251    /* retrieve stream information */
252    if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
253        fprintf(stderr, "Could not find stream information\n");
254        exit(1);
255    }
256
257    if (open_codec_context(&video_stream_idx, &video_dec_ctx, fmt_ctx, AVMEDIA_TYPE_VIDEO) >= 0) {
258        video_stream = fmt_ctx->streams[video_stream_idx];
259
260        video_dst_file = fopen(video_dst_filename, "wb");
261        if (!video_dst_file) {
262            fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
263            ret = 1;
264            goto end;
265        }
266
267        /* allocate image where the decoded image will be put */
268        width = video_dec_ctx->width;
269        height = video_dec_ctx->height;
270        pix_fmt = video_dec_ctx->pix_fmt;
271        ret = av_image_alloc(video_dst_data, video_dst_linesize,
272                             width, height, pix_fmt, 1);
273        if (ret < 0) {
274            fprintf(stderr, "Could not allocate raw video buffer\n");
275            goto end;
276        }
277        video_dst_bufsize = ret;
278    }
279
280    if (open_codec_context(&audio_stream_idx, &audio_dec_ctx, fmt_ctx, AVMEDIA_TYPE_AUDIO) >= 0) {
281        audio_stream = fmt_ctx->streams[audio_stream_idx];
282        audio_dst_file = fopen(audio_dst_filename, "wb");
283        if (!audio_dst_file) {
284            fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename);
285            ret = 1;
286            goto end;
287        }
288    }
289
290    /* dump input information to stderr */
291    av_dump_format(fmt_ctx, 0, src_filename, 0);
292
293    if (!audio_stream && !video_stream) {
294        fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
295        ret = 1;
296        goto end;
297    }
298
299    frame = av_frame_alloc();
300    if (!frame) {
301        fprintf(stderr, "Could not allocate frame\n");
302        ret = AVERROR(ENOMEM);
303        goto end;
304    }
305
306    pkt = av_packet_alloc();
307    if (!pkt) {
308        fprintf(stderr, "Could not allocate packet\n");
309        ret = AVERROR(ENOMEM);
310        goto end;
311    }
312
313    if (video_stream)
314        printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);
315    if (audio_stream)
316        printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename);
317
318    /* read frames from the file */
319    while (av_read_frame(fmt_ctx, pkt) >= 0) {
320        // check if the packet belongs to a stream we are interested in, otherwise
321        // skip it
322        if (pkt->stream_index == video_stream_idx)
323            ret = decode_packet(video_dec_ctx, pkt);
324        else if (pkt->stream_index == audio_stream_idx)
325            ret = decode_packet(audio_dec_ctx, pkt);
326        av_packet_unref(pkt);
327        if (ret < 0)
328            break;
329    }
330
331    /* flush the decoders */
332    if (video_dec_ctx)
333        decode_packet(video_dec_ctx, NULL);
334    if (audio_dec_ctx)
335        decode_packet(audio_dec_ctx, NULL);
336
337    printf("Demuxing succeeded.\n");
338
339    if (video_stream) {
340        printf("Play the output video file with the command:\n"
341               "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
342               av_get_pix_fmt_name(pix_fmt), width, height,
343               video_dst_filename);
344    }
345
346    if (audio_stream) {
347        enum AVSampleFormat sfmt = audio_dec_ctx->sample_fmt;
348        int n_channels = audio_dec_ctx->ch_layout.nb_channels;
349        const char *fmt;
350
351        if (av_sample_fmt_is_planar(sfmt)) {
352            const char *packed = av_get_sample_fmt_name(sfmt);
353            printf("Warning: the sample format the decoder produced is planar "
354                   "(%s). This example will output the first channel only.\n",
355                   packed ? packed : "?");
356            sfmt = av_get_packed_sample_fmt(sfmt);
357            n_channels = 1;
358        }
359
360        if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0)
361            goto end;
362
363        printf("Play the output audio file with the command:\n"
364               "ffplay -f %s -ac %d -ar %d %s\n",
365               fmt, n_channels, audio_dec_ctx->sample_rate,
366               audio_dst_filename);
367    }
368
369end:
370    avcodec_free_context(&video_dec_ctx);
371    avcodec_free_context(&audio_dec_ctx);
372    avformat_close_input(&fmt_ctx);
373    if (video_dst_file)
374        fclose(video_dst_file);
375    if (audio_dst_file)
376        fclose(audio_dst_file);
377    av_packet_free(&pkt);
378    av_frame_free(&frame);
379    av_free(video_dst_data[0]);
380
381    return ret < 0;
382}
383