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Diffstat (limited to 'doc/examples/demuxing_decoding.c')
| -rw-r--r-- | doc/examples/demuxing_decoding.c | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/doc/examples/demuxing_decoding.c b/doc/examples/demuxing_decoding.c new file mode 100644 index 0000000000..b1a216abb4 --- /dev/null +++ b/doc/examples/demuxing_decoding.c @@ -0,0 +1,393 @@ +/* + * Copyright (c) 2012 Stefano Sabatini + * + * 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 + * Demuxing and decoding example. + * + * Show how to use the libavformat and libavcodec API to demux and + * decode audio and video data. + * @example demuxing_decoding.c + */ + +#include <libavutil/imgutils.h> +#include <libavutil/samplefmt.h> +#include <libavutil/timestamp.h> +#include <libavformat/avformat.h> + +static AVFormatContext *fmt_ctx = NULL; +static AVCodecContext *video_dec_ctx = NULL, *audio_dec_ctx; +static int width, height; +static enum AVPixelFormat pix_fmt; +static AVStream *video_stream = NULL, *audio_stream = NULL; +static const char *src_filename = NULL; +static const char *video_dst_filename = NULL; +static const char *audio_dst_filename = NULL; +static FILE *video_dst_file = NULL; +static FILE *audio_dst_file = NULL; + +static uint8_t *video_dst_data[4] = {NULL}; +static int video_dst_linesize[4]; +static int video_dst_bufsize; + +static int video_stream_idx = -1, audio_stream_idx = -1; +static AVFrame *frame = NULL; +static AVPacket pkt; +static int video_frame_count = 0; +static int audio_frame_count = 0; + +/* Enable or disable frame reference counting. You are not supposed to support + * both paths in your application but pick the one most appropriate to your + * needs. Look for the use of refcount in this example to see what are the + * differences of API usage between them. */ +static int refcount = 0; + +static int decode_packet(int *got_frame, int cached) +{ + int ret = 0; + int decoded = pkt.size; + + *got_frame = 0; + + if (pkt.stream_index == video_stream_idx) { + /* decode video frame */ + ret = avcodec_decode_video2(video_dec_ctx, frame, got_frame, &pkt); + if (ret < 0) { + fprintf(stderr, "Error decoding video frame (%s)\n", av_err2str(ret)); + return ret; + } + + if (*got_frame) { + + if (frame->width != width || frame->height != height || + frame->format != pix_fmt) { + /* To handle this change, one could call av_image_alloc again and + * decode the following frames into another rawvideo file. */ + fprintf(stderr, "Error: Width, height and pixel format have to be " + "constant in a rawvideo file, but the width, height or " + "pixel format of the input video changed:\n" + "old: width = %d, height = %d, format = %s\n" + "new: width = %d, height = %d, format = %s\n", + width, height, av_get_pix_fmt_name(pix_fmt), + frame->width, frame->height, + av_get_pix_fmt_name(frame->format)); + return -1; + } + + printf("video_frame%s n:%d coded_n:%d\n", + cached ? "(cached)" : "", + video_frame_count++, frame->coded_picture_number); + + /* copy decoded frame to destination buffer: + * this is required since rawvideo expects non aligned data */ + av_image_copy(video_dst_data, video_dst_linesize, + (const uint8_t **)(frame->data), frame->linesize, + pix_fmt, width, height); + + /* write to rawvideo file */ + fwrite(video_dst_data[0], 1, video_dst_bufsize, video_dst_file); + } + } else if (pkt.stream_index == audio_stream_idx) { + /* decode audio frame */ + ret = avcodec_decode_audio4(audio_dec_ctx, frame, got_frame, &pkt); + if (ret < 0) { + fprintf(stderr, "Error decoding audio frame (%s)\n", av_err2str(ret)); + return ret; + } + /* Some audio decoders decode only part of the packet, and have to be + * called again with the remainder of the packet data. + * Sample: fate-suite/lossless-audio/luckynight-partial.shn + * Also, some decoders might over-read the packet. */ + decoded = FFMIN(ret, pkt.size); + + if (*got_frame) { + size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format); + printf("audio_frame%s n:%d nb_samples:%d pts:%s\n", + cached ? "(cached)" : "", + audio_frame_count++, frame->nb_samples, + av_ts2timestr(frame->pts, &audio_dec_ctx->time_base)); + + /* Write the raw audio data samples of the first plane. This works + * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However, + * most audio decoders output planar audio, which uses a separate + * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P). + * In other words, this code will write only the first audio channel + * in these cases. + * You should use libswresample or libavfilter to convert the frame + * to packed data. */ + fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file); + } + } + + /* If we use frame reference counting, we own the data and need + * to de-reference it when we don't use it anymore */ + if (*got_frame && refcount) + av_frame_unref(frame); + + return decoded; +} + +static int open_codec_context(int *stream_idx, + AVCodecContext **dec_ctx, AVFormatContext *fmt_ctx, enum AVMediaType type) +{ + int ret, stream_index; + AVStream *st; + AVCodec *dec = NULL; + AVDictionary *opts = NULL; + + ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0); + if (ret < 0) { + fprintf(stderr, "Could not find %s stream in input file '%s'\n", + av_get_media_type_string(type), src_filename); + return ret; + } else { + stream_index = ret; + st = fmt_ctx->streams[stream_index]; + + /* find decoder for the stream */ + dec = avcodec_find_decoder(st->codecpar->codec_id); + if (!dec) { + fprintf(stderr, "Failed to find %s codec\n", + av_get_media_type_string(type)); + return AVERROR(EINVAL); + } + + /* Allocate a codec context for the decoder */ + *dec_ctx = avcodec_alloc_context3(dec); + if (!*dec_ctx) { + fprintf(stderr, "Failed to allocate the %s codec context\n", + av_get_media_type_string(type)); + return AVERROR(ENOMEM); + } + + /* Copy codec parameters from input stream to output codec context */ + if ((ret = avcodec_parameters_to_context(*dec_ctx, st->codecpar)) < 0) { + fprintf(stderr, "Failed to copy %s codec parameters to decoder context\n", + av_get_media_type_string(type)); + return ret; + } + + /* Init the decoders, with or without reference counting */ + av_dict_set(&opts, "refcounted_frames", refcount ? "1" : "0", 0); + if ((ret = avcodec_open2(*dec_ctx, dec, &opts)) < 0) { + fprintf(stderr, "Failed to open %s codec\n", + av_get_media_type_string(type)); + return ret; + } + *stream_idx = stream_index; + } + + return 0; +} + +static int get_format_from_sample_fmt(const char **fmt, + enum AVSampleFormat sample_fmt) +{ + int i; + struct sample_fmt_entry { + enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le; + } sample_fmt_entries[] = { + { AV_SAMPLE_FMT_U8, "u8", "u8" }, + { AV_SAMPLE_FMT_S16, "s16be", "s16le" }, + { AV_SAMPLE_FMT_S32, "s32be", "s32le" }, + { AV_SAMPLE_FMT_FLT, "f32be", "f32le" }, + { AV_SAMPLE_FMT_DBL, "f64be", "f64le" }, + }; + *fmt = NULL; + + for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) { + struct sample_fmt_entry *entry = &sample_fmt_entries[i]; + if (sample_fmt == entry->sample_fmt) { + *fmt = AV_NE(entry->fmt_be, entry->fmt_le); + return 0; + } + } + + fprintf(stderr, + "sample format %s is not supported as output format\n", + av_get_sample_fmt_name(sample_fmt)); + return -1; +} + +int main (int argc, char **argv) +{ + int ret = 0, got_frame; + + if (argc != 4 && argc != 5) { + fprintf(stderr, "usage: %s [-refcount] input_file video_output_file audio_output_file\n" + "API example program to show how to read frames from an input file.\n" + "This program reads frames from a file, decodes them, and writes decoded\n" + "video frames to a rawvideo file named video_output_file, and decoded\n" + "audio frames to a rawaudio file named audio_output_file.\n\n" + "If the -refcount option is specified, the program use the\n" + "reference counting frame system which allows keeping a copy of\n" + "the data for longer than one decode call.\n" + "\n", argv[0]); + exit(1); + } + if (argc == 5 && !strcmp(argv[1], "-refcount")) { + refcount = 1; + argv++; + } + src_filename = argv[1]; + video_dst_filename = argv[2]; + audio_dst_filename = argv[3]; + + /* register all formats and codecs */ + av_register_all(); + + /* open input file, and allocate format context */ + if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) { + fprintf(stderr, "Could not open source file %s\n", src_filename); + exit(1); + } + + /* retrieve stream information */ + if (avformat_find_stream_info(fmt_ctx, NULL) < 0) { + fprintf(stderr, "Could not find stream information\n"); + exit(1); + } + + if (open_codec_context(&video_stream_idx, &video_dec_ctx, fmt_ctx, AVMEDIA_TYPE_VIDEO) >= 0) { + video_stream = fmt_ctx->streams[video_stream_idx]; + + video_dst_file = fopen(video_dst_filename, "wb"); + if (!video_dst_file) { + fprintf(stderr, "Could not open destination file %s\n", video_dst_filename); + ret = 1; + goto end; + } + + /* allocate image where the decoded image will be put */ + width = video_dec_ctx->width; + height = video_dec_ctx->height; + pix_fmt = video_dec_ctx->pix_fmt; + ret = av_image_alloc(video_dst_data, video_dst_linesize, + width, height, pix_fmt, 1); + if (ret < 0) { + fprintf(stderr, "Could not allocate raw video buffer\n"); + goto end; + } + video_dst_bufsize = ret; + } + + if (open_codec_context(&audio_stream_idx, &audio_dec_ctx, fmt_ctx, AVMEDIA_TYPE_AUDIO) >= 0) { + audio_stream = fmt_ctx->streams[audio_stream_idx]; + audio_dst_file = fopen(audio_dst_filename, "wb"); + if (!audio_dst_file) { + fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename); + ret = 1; + goto end; + } + } + + /* dump input information to stderr */ + av_dump_format(fmt_ctx, 0, src_filename, 0); + + if (!audio_stream && !video_stream) { + fprintf(stderr, "Could not find audio or video stream in the input, aborting\n"); + ret = 1; + goto end; + } + + frame = av_frame_alloc(); + if (!frame) { + fprintf(stderr, "Could not allocate frame\n"); + ret = AVERROR(ENOMEM); + goto end; + } + + /* initialize packet, set data to NULL, let the demuxer fill it */ + av_init_packet(&pkt); + pkt.data = NULL; + pkt.size = 0; + + if (video_stream) + printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename); + if (audio_stream) + printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename); + + /* read frames from the file */ + while (av_read_frame(fmt_ctx, &pkt) >= 0) { + AVPacket orig_pkt = pkt; + do { + ret = decode_packet(&got_frame, 0); + if (ret < 0) + break; + pkt.data += ret; + pkt.size -= ret; + } while (pkt.size > 0); + av_packet_unref(&orig_pkt); + } + + /* flush cached frames */ + pkt.data = NULL; + pkt.size = 0; + do { + decode_packet(&got_frame, 1); + } while (got_frame); + + printf("Demuxing succeeded.\n"); + + if (video_stream) { + printf("Play the output video file with the command:\n" + "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n", + av_get_pix_fmt_name(pix_fmt), width, height, + video_dst_filename); + } + + if (audio_stream) { + enum AVSampleFormat sfmt = audio_dec_ctx->sample_fmt; + int n_channels = audio_dec_ctx->channels; + const char *fmt; + + if (av_sample_fmt_is_planar(sfmt)) { + const char *packed = av_get_sample_fmt_name(sfmt); + printf("Warning: the sample format the decoder produced is planar " + "(%s). This example will output the first channel only.\n", + packed ? packed : "?"); + sfmt = av_get_packed_sample_fmt(sfmt); + n_channels = 1; + } + + if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0) + goto end; + + printf("Play the output audio file with the command:\n" + "ffplay -f %s -ac %d -ar %d %s\n", + fmt, n_channels, audio_dec_ctx->sample_rate, + audio_dst_filename); + } + +end: + avcodec_free_context(&video_dec_ctx); + avcodec_free_context(&audio_dec_ctx); + avformat_close_input(&fmt_ctx); + if (video_dst_file) + fclose(video_dst_file); + if (audio_dst_file) + fclose(audio_dst_file); + av_frame_free(&frame); + av_free(video_dst_data[0]); + + return ret < 0; +} |