[FFmpeg-devel] [PATCH] examples/demuxing: add audio decoding/demuxing
Stefano Sabatini
stefasab at gmail.com
Sat Sep 8 00:02:18 CEST 2012
---
doc/examples/demuxing.c | 302 ++++++++++++++++++++++++++++++++++-------------
1 files changed, 222 insertions(+), 80 deletions(-)
diff --git a/doc/examples/demuxing.c b/doc/examples/demuxing.c
index fca7feb..85839f2 100644
--- a/doc/examples/demuxing.c
+++ b/doc/examples/demuxing.c
@@ -25,75 +25,184 @@
* libavformat demuxing API use example.
*
* Show how to use the libavformat and libavcodec API to demux and
- * decode video data.
+ * decode audio and video data.
*/
#include <libavutil/imgutils.h>
+#include <libavutil/samplefmt.h>
#include <libavutil/timestamp.h>
#include <libavformat/avformat.h>
static AVFormatContext *fmt_ctx = NULL;
-static AVCodecContext *dec_ctx = NULL;
-static AVCodec *dec = NULL;
-static AVStream *stream = NULL;
+static AVCodecContext *video_dec_ctx = NULL, *audio_dec_ctx;
+static AVStream *video_stream = NULL, *audio_stream = NULL;
static const char *src_filename = NULL;
-static const char *dst_filename = NULL;
-static FILE *dst_file = NULL;
-static uint8_t *dst_data[4] = {NULL};
-static int dst_linesize[4];
-static int dst_bufsize;
-static int stream_idx;
+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 uint8_t **audio_dst_data = NULL;
+static int audio_dst_linesize;
+static int audio_dst_bufsize;
+
+static int video_stream_idx = -1, audio_stream_idx = -1;
static AVFrame *frame = NULL;
static AVPacket pkt;
-static int frame_count = 0;
+static int video_frame_count = 0;
+static int audio_frame_count = 0;
static int decode_packet(int *got_frame, int cached)
{
- int ret;
+ int ret = 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\n");
+ return ret;
+ }
+
+ if (*got_frame) {
+ printf("video_frame%s n:%d coded_n:%d pts:%s\n",
+ cached ? "(cached)" : "",
+ video_frame_count++, frame->coded_picture_number,
+ av_ts2timestr(frame->pts, &video_dec_ctx->time_base));
+
+ /* 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,
+ video_dec_ctx->pix_fmt, video_dec_ctx->width, video_dec_ctx->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\n");
+ return ret;
+ }
+
+ if (*got_frame) {
+ 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));
+
+ ret = av_samples_alloc(audio_dst_data, &audio_dst_linesize, frame->channels,
+ frame->nb_samples, frame->format, 1);
+ if (ret < 0) {
+ fprintf(stderr, "Could not allocate audio buffer\n");
+ return AVERROR(ENOMEM);
+ }
+
+ /* TODO: extend return code of the av_samples_* functions so that this is not needed */
+ audio_dst_bufsize =
+ av_samples_get_buffer_size(NULL, frame->channels,
+ frame->nb_samples, frame->format, 1);
+
+ /* copy audio data to destination buffer:
+ * this is required since rawaudio expects non aligned data */
+ av_samples_copy(audio_dst_data, frame->data, 0, 0,
+ frame->nb_samples, frame->channels, frame->format);
- if (pkt.stream_index != stream_idx)
- return 0;
+ /* write to rawaudio file */
+ fwrite(audio_dst_data[0], 1, audio_dst_bufsize, audio_dst_file);
+ av_freep(&audio_dst_data[0]);
+ }
+ }
+
+ return ret;
+}
+
+static int open_codec_context(int *stream_idx,
+ AVFormatContext *fmt_ctx, enum AVMediaType type)
+{
+ int ret;
+ AVStream *st;
+ AVCodecContext *dec_ctx = NULL;
+ AVCodec *dec = NULL;
- /* decode video frame */
- ret = avcodec_decode_video2(dec_ctx, frame, got_frame, &pkt);
+ ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
if (ret < 0) {
- fprintf(stderr, "Error decoding video frame\n");
- return ret;
+ fprintf(stderr, "Could not find %s stream in file\n",
+ av_get_media_type_string(type));
+ } else {
+ *stream_idx = ret;
+ st = fmt_ctx->streams[*stream_idx];
+
+ /* find decoder for the stream */
+ dec_ctx = st->codec;
+ dec = avcodec_find_decoder(dec_ctx->codec_id);
+ if (!dec) {
+ fprintf(stderr, "Failed to find %s codec\n",
+ av_get_media_type_string(type));
+ return ret;
+ }
+
+ if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
+ fprintf(stderr, "Failed to open %s codec\n",
+ av_get_media_type_string(type));
+ return ret;
+ }
}
- if (*got_frame) {
- printf("frame%s n:%d coded_n:%d pts:%s\n",
- cached ? "(cached)" : "",
- frame_count++, frame->coded_picture_number,
- av_ts2timestr(frame->pts, &dec_ctx->time_base));
+ return 0;
+}
- /* copy decoded frame to destination buffer:
- * this is required since rawvideo expect non aligned data */
- av_image_copy(dst_data, dst_linesize,
- (const uint8_t **)(frame->data), frame->linesize,
- dec_ctx->pix_fmt, dec_ctx->width, dec_ctx->height);
+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;
- /* write to rawvideo file */
- fwrite(dst_data[0], 1, dst_bufsize, dst_file);
+ 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;
+ }
}
- return ret;
+ 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, got_frame;
+ int ret = 0, got_frame;
- if (argc != 3) {
- fprintf(stderr, "usage: %s input_file output_file\n"
+ if (argc != 4) {
+ fprintf(stderr, "usage: %s 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, decode them, and write them "
- "to a rawvideo file named like output_file."
+ "This program reads frames from a file, decode them, and write decoded video "
+ "frames to a rawvideo file named video_output_file, and decoded audio frames "
+ "to a rawaudio file named audio_output_file.\n"
"\n", argv[0]);
exit(1);
}
src_filename = argv[1];
- dst_filename = argv[2];
+ video_dst_filename = argv[2];
+ audio_dst_filename = argv[3];
/* register all formats and codecs */
av_register_all();
@@ -110,60 +219,74 @@ int main (int argc, char **argv)
exit(1);
}
- ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);
- if (ret < 0) {
- fprintf(stderr, "Could not find video stream in file\n");
- goto end;
- }
- stream_idx = ret;
- stream = fmt_ctx->streams[stream_idx];
-
- /* find decoder for the stream */
- dec_ctx = stream->codec;
- dec = avcodec_find_decoder(dec_ctx->codec_id);
- if (!dec) {
- fprintf(stderr, "Failed to find any codec\n");
- ret = 1;
- goto end;
- }
+ if (open_codec_context(&video_stream_idx, fmt_ctx, AVMEDIA_TYPE_VIDEO) >= 0) {
+ video_stream = fmt_ctx->streams[video_stream_idx];
+ video_dec_ctx = video_stream->codec;
- if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
- fprintf(stderr, "Failed to open codec\n");
- goto end;
+ 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 */
+ ret = av_image_alloc(video_dst_data, video_dst_linesize,
+ video_dec_ctx->width, video_dec_ctx->height,
+ video_dec_ctx->pix_fmt, 1);
+ if (ret < 0) {
+ fprintf(stderr, "Could not allocate raw video buffer\n");
+ goto end;
+ }
+ video_dst_bufsize = ret;
}
/* dump input information to stderr */
av_dump_format(fmt_ctx, 0, src_filename, 0);
- dst_file = fopen(dst_filename, "wb");
- if (!dst_file) {
- fprintf(stderr, "Could not open destination file %s\n", dst_filename);
- ret = 1;
- goto end;
+ if (open_codec_context(&audio_stream_idx, fmt_ctx, AVMEDIA_TYPE_AUDIO) >= 0) {
+ int packed;
+
+ audio_stream = fmt_ctx->streams[audio_stream_idx];
+ audio_dec_ctx = audio_stream->codec;
+ audio_dst_file = fopen(audio_dst_filename, "wb");
+ if (!audio_dst_file) {
+ fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
+ ret = 1;
+ goto end;
+ }
+
+ packed = av_get_packed_sample_fmt(audio_dec_ctx->sample_fmt) == audio_dec_ctx->sample_fmt;
+ audio_dst_data = av_mallocz(sizeof(uint8_t *) * packed ? 1 : audio_dec_ctx->channels);
+ if (!audio_dst_data) {
+ fprintf(stderr, "Could not allocate audio data buffers\n");
+ ret = AVERROR(ENOMEM);
+ goto end;
+ }
}
- frame = avcodec_alloc_frame();
- if (!frame) {
- fprintf(stderr, "Could not allocate video frame\n");
+ if (!audio_stream && !video_stream) {
+ fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
ret = 1;
goto end;
}
- /* allocate image where the decoded image will be put */
- ret = av_image_alloc(dst_data, dst_linesize,
- dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt, 1);
- if (ret < 0) {
- fprintf(stderr, "Could not alloc raw video buffer\n");
+ frame = avcodec_alloc_frame();
+ if (!frame) {
+ fprintf(stderr, "Could not allocate frame\n");
+ ret = AVERROR(ENOMEM);
goto end;
}
- dst_bufsize = ret;
/* initialize packet, set data to NULL, let the demuxer fill it */
av_init_packet(&pkt);
- pkt.size = 0;
pkt.data = NULL;
+ pkt.size = 0;
- printf("Demuxing file '%s' to '%s'\n", src_filename, dst_filename);
+ if (video_stream)
+ printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);
+ if (audio_stream)
+ printf("Demuxing video from file '%s' into '%s'\n", src_filename, audio_dst_filename);
/* read frames from the file */
while (av_read_frame(fmt_ctx, &pkt) >= 0)
@@ -176,18 +299,37 @@ int main (int argc, char **argv)
decode_packet(&got_frame, 1);
} while (got_frame);
- printf("Demuxing succeeded. Play the output file with the command:\n"
- "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
- av_get_pix_fmt_name(dec_ctx->pix_fmt), dec_ctx->width, dec_ctx->height,
- dst_filename);
+ 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(video_dec_ctx->pix_fmt), video_dec_ctx->width, video_dec_ctx->height,
+ video_dst_filename);
+ }
+
+ if (audio_stream) {
+ const char *fmt;
+
+ if ((ret = get_format_from_sample_fmt(&fmt, audio_dec_ctx->sample_fmt) < 0))
+ goto end;
+ printf("Play the output audio file with the command:\n"
+ "ffplay -f %s -ac %d -ar %d %s\n",
+ fmt, audio_dec_ctx->channels, audio_dec_ctx->sample_rate,
+ audio_dst_filename);
+ }
end:
- avcodec_close(dec_ctx);
+ avcodec_close(video_dec_ctx);
+ avcodec_close(audio_dec_ctx);
avformat_close_input(&fmt_ctx);
- if (dst_file)
- fclose(dst_file);
+ if (video_dst_file)
+ fclose(video_dst_file);
+ if (audio_dst_file)
+ fclose(audio_dst_file);
av_free(frame);
- av_free(dst_data[0]);
+ av_free(video_dst_data[0]);
+ av_free(audio_dst_data);
return ret < 0;
}
--
1.7.5.4
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