[FFmpeg-devel] [PATCH] examples/demuxing: add audio decoding/demuxing
Takis Issaris
takis.issaris at uhasselt.be
Mon Sep 10 10:55:12 CEST 2012
Hi Stefano,
2012/9/8 Stefano Sabatini <stefasab at gmail.com>:
> ---
> doc/examples/demuxing.c | 302 ++++++++++++++++++++++++++++++++++-------------
> 1 files changed, 222 insertions(+), 80 deletions(-)
IMHO it would be better to add this as a separate example, so the
original very simple single stream example is still available to new
users of the FFmpeg libraries.
With friendly regards,
Takis
>
> 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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> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
--
Met vriendelijke groeten,
Takis
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