[FFmpeg-devel] [PATCH] examples/transcoding: convert to codecpar
James Almer
jamrial at gmail.com
Sat Aug 27 21:15:44 EEST 2016
Signed-off-by: James Almer <jamrial at gmail.com>
---
This example is kinda broken, before and after this patch. The files it
creates are not always correct, at least with video using the most common
containers.
If i were to guess, it's probably why ffmpeg.c has so many container and
codec specific workarounds beyond what the libraries themselves do.
doc/examples/transcoding.c | 94 ++++++++++++++++++++++++++++++++--------------
1 file changed, 65 insertions(+), 29 deletions(-)
diff --git a/doc/examples/transcoding.c b/doc/examples/transcoding.c
index 8633362..5a648e4 100644
--- a/doc/examples/transcoding.c
+++ b/doc/examples/transcoding.c
@@ -45,6 +45,12 @@ typedef struct FilteringContext {
} FilteringContext;
static FilteringContext *filter_ctx;
+typedef struct StreamContext {
+ AVCodecContext *dec_ctx;
+ AVCodecContext *enc_ctx;
+} StreamContext;
+static StreamContext *stream_ctx;
+
static int open_input_file(const char *filename)
{
int ret;
@@ -61,22 +67,41 @@ static int open_input_file(const char *filename)
return ret;
}
+ stream_ctx = av_mallocz_array(ifmt_ctx->nb_streams, sizeof(*stream_ctx));
+ if (!stream_ctx)
+ return AVERROR(ENOMEM);
+
for (i = 0; i < ifmt_ctx->nb_streams; i++) {
- AVStream *stream;
+ AVStream *stream = ifmt_ctx->streams[i];
+ AVCodec *dec = avcodec_find_decoder(stream->codecpar->codec_id);
AVCodecContext *codec_ctx;
- stream = ifmt_ctx->streams[i];
- codec_ctx = stream->codec;
+ if (!dec) {
+ av_log(NULL, AV_LOG_ERROR, "Failed to find decoder for stream #%u\n", i);
+ return AVERROR_DECODER_NOT_FOUND;
+ }
+ codec_ctx = avcodec_alloc_context3(dec);
+ if (!codec_ctx) {
+ av_log(NULL, AV_LOG_ERROR, "Failed to allocate the decoder context for stream #%u\n", i);
+ return AVERROR(ENOMEM);
+ }
+ if ((ret = avcodec_parameters_to_context(codec_ctx, stream->codecpar)) < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Failed to copy decoder parameters to input decoder context "
+ "for stream #%u\n", i);
+ return ret;
+ }
/* Reencode video & audio and remux subtitles etc. */
if (codec_ctx->codec_type == AVMEDIA_TYPE_VIDEO
|| codec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
+ if (codec_ctx->codec_type == AVMEDIA_TYPE_VIDEO)
+ codec_ctx->framerate = av_guess_frame_rate(ifmt_ctx, stream, NULL);
/* Open decoder */
- ret = avcodec_open2(codec_ctx,
- avcodec_find_decoder(codec_ctx->codec_id), NULL);
+ ret = avcodec_open2(codec_ctx, dec, NULL);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Failed to open decoder for stream #%u\n", i);
return ret;
}
}
+ stream_ctx[i].dec_ctx = codec_ctx;
}
av_dump_format(ifmt_ctx, 0, filename, 0);
@@ -108,8 +133,7 @@ static int open_output_file(const char *filename)
}
in_stream = ifmt_ctx->streams[i];
- dec_ctx = in_stream->codec;
- enc_ctx = out_stream->codec;
+ dec_ctx = stream_ctx[i].dec_ctx;
if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO
|| dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
@@ -119,6 +143,11 @@ static int open_output_file(const char *filename)
av_log(NULL, AV_LOG_FATAL, "Necessary encoder not found\n");
return AVERROR_INVALIDDATA;
}
+ enc_ctx = avcodec_alloc_context3(encoder);
+ if (!enc_ctx) {
+ av_log(NULL, AV_LOG_FATAL, "Failed to allocate the encoder context\n");
+ return AVERROR(ENOMEM);
+ }
/* In this example, we transcode to same properties (picture size,
* sample rate etc.). These properties can be changed for output
@@ -133,7 +162,7 @@ static int open_output_file(const char *filename)
else
enc_ctx->pix_fmt = dec_ctx->pix_fmt;
/* video time_base can be set to whatever is handy and supported by encoder */
- enc_ctx->time_base = dec_ctx->time_base;
+ enc_ctx->time_base = av_inv_q(dec_ctx->framerate);
} else {
enc_ctx->sample_rate = dec_ctx->sample_rate;
enc_ctx->channel_layout = dec_ctx->channel_layout;
@@ -149,22 +178,28 @@ static int open_output_file(const char *filename)
av_log(NULL, AV_LOG_ERROR, "Cannot open video encoder for stream #%u\n", i);
return ret;
}
+ if ((ret = avcodec_parameters_from_context(out_stream->codecpar, enc_ctx)) < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Failed to copy encoder parameters to output stream #%u\n", i);
+ return ret;
+ }
+ if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
+ enc_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
+
+ out_stream->time_base = enc_ctx->time_base;
+ stream_ctx[i].enc_ctx = enc_ctx;
} else if (dec_ctx->codec_type == AVMEDIA_TYPE_UNKNOWN) {
av_log(NULL, AV_LOG_FATAL, "Elementary stream #%d is of unknown type, cannot proceed\n", i);
return AVERROR_INVALIDDATA;
} else {
/* if this stream must be remuxed */
- ret = avcodec_copy_context(ofmt_ctx->streams[i]->codec,
- ifmt_ctx->streams[i]->codec);
+ ret = avcodec_parameters_copy(out_stream->codecpar, in_stream->codecpar);
if (ret < 0) {
- av_log(NULL, AV_LOG_ERROR, "Copying stream context failed\n");
+ av_log(NULL, AV_LOG_ERROR, "Copying parameters for stream #%u failed\n", i);
return ret;
}
+ out_stream->time_base = in_stream->time_base;
}
- if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
- enc_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
-
}
av_dump_format(ofmt_ctx, 0, filename, 1);
@@ -348,17 +383,17 @@ static int init_filters(void)
filter_ctx[i].buffersrc_ctx = NULL;
filter_ctx[i].buffersink_ctx = NULL;
filter_ctx[i].filter_graph = NULL;
- if (!(ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO
- || ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO))
+ if (!(ifmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO
+ || ifmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO))
continue;
- if (ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
+ if (ifmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
filter_spec = "null"; /* passthrough (dummy) filter for video */
else
filter_spec = "anull"; /* passthrough (dummy) filter for audio */
- ret = init_filter(&filter_ctx[i], ifmt_ctx->streams[i]->codec,
- ofmt_ctx->streams[i]->codec, filter_spec);
+ ret = init_filter(&filter_ctx[i], stream_ctx[i].dec_ctx,
+ stream_ctx[i].enc_ctx, filter_spec);
if (ret)
return ret;
}
@@ -370,7 +405,7 @@ static int encode_write_frame(AVFrame *filt_frame, unsigned int stream_index, in
int got_frame_local;
AVPacket enc_pkt;
int (*enc_func)(AVCodecContext *, AVPacket *, const AVFrame *, int *) =
- (ifmt_ctx->streams[stream_index]->codec->codec_type ==
+ (ifmt_ctx->streams[stream_index]->codecpar->codec_type ==
AVMEDIA_TYPE_VIDEO) ? avcodec_encode_video2 : avcodec_encode_audio2;
if (!got_frame)
@@ -381,7 +416,7 @@ static int encode_write_frame(AVFrame *filt_frame, unsigned int stream_index, in
enc_pkt.data = NULL;
enc_pkt.size = 0;
av_init_packet(&enc_pkt);
- ret = enc_func(ofmt_ctx->streams[stream_index]->codec, &enc_pkt,
+ ret = enc_func(stream_ctx[stream_index].enc_ctx, &enc_pkt,
filt_frame, got_frame);
av_frame_free(&filt_frame);
if (ret < 0)
@@ -392,7 +427,7 @@ static int encode_write_frame(AVFrame *filt_frame, unsigned int stream_index, in
/* prepare packet for muxing */
enc_pkt.stream_index = stream_index;
av_packet_rescale_ts(&enc_pkt,
- ofmt_ctx->streams[stream_index]->codec->time_base,
+ stream_ctx[stream_index].enc_ctx->time_base,
ofmt_ctx->streams[stream_index]->time_base);
av_log(NULL, AV_LOG_DEBUG, "Muxing frame\n");
@@ -450,7 +485,7 @@ static int flush_encoder(unsigned int stream_index)
int ret;
int got_frame;
- if (!(ofmt_ctx->streams[stream_index]->codec->codec->capabilities &
+ if (!(stream_ctx[stream_index].enc_ctx->codec->capabilities &
AV_CODEC_CAP_DELAY))
return 0;
@@ -496,7 +531,7 @@ int main(int argc, char **argv)
if ((ret = av_read_frame(ifmt_ctx, &packet)) < 0)
break;
stream_index = packet.stream_index;
- type = ifmt_ctx->streams[packet.stream_index]->codec->codec_type;
+ type = ifmt_ctx->streams[packet.stream_index]->codecpar->codec_type;
av_log(NULL, AV_LOG_DEBUG, "Demuxer gave frame of stream_index %u\n",
stream_index);
@@ -509,10 +544,10 @@ int main(int argc, char **argv)
}
av_packet_rescale_ts(&packet,
ifmt_ctx->streams[stream_index]->time_base,
- ifmt_ctx->streams[stream_index]->codec->time_base);
+ stream_ctx[stream_index].dec_ctx->time_base);
dec_func = (type == AVMEDIA_TYPE_VIDEO) ? avcodec_decode_video2 :
avcodec_decode_audio4;
- ret = dec_func(ifmt_ctx->streams[stream_index]->codec, frame,
+ ret = dec_func(stream_ctx[stream_index].dec_ctx, frame,
&got_frame, &packet);
if (ret < 0) {
av_frame_free(&frame);
@@ -566,13 +601,14 @@ end:
av_packet_unref(&packet);
av_frame_free(&frame);
for (i = 0; i < ifmt_ctx->nb_streams; i++) {
- avcodec_close(ifmt_ctx->streams[i]->codec);
- if (ofmt_ctx && ofmt_ctx->nb_streams > i && ofmt_ctx->streams[i] && ofmt_ctx->streams[i]->codec)
- avcodec_close(ofmt_ctx->streams[i]->codec);
+ avcodec_free_context(&stream_ctx[i].dec_ctx);
+ if (ofmt_ctx && ofmt_ctx->nb_streams > i && ofmt_ctx->streams[i] && stream_ctx[i].enc_ctx)
+ avcodec_free_context(&stream_ctx[i].enc_ctx);
if (filter_ctx && filter_ctx[i].filter_graph)
avfilter_graph_free(&filter_ctx[i].filter_graph);
}
av_free(filter_ctx);
+ av_free(stream_ctx);
avformat_close_input(&ifmt_ctx);
if (ofmt_ctx && !(ofmt_ctx->oformat->flags & AVFMT_NOFILE))
avio_closep(&ofmt_ctx->pb);
--
2.9.1
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