#3107: Problem using muxing example
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Reporter: ahsan | Owner:
Type: defect | Status: new
Priority: normal | Component:
Version: unspecified | undetermined
Keywords: | Resolution:
Blocking: | Blocked By:
Analyzed by developer: 0 | Reproduced by developer: 0
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Comment (by ahsan):
I merged, demux and mux example codes so that i can take in any
.mp4/.avi/mpg files and then re-encode them in the same format
I am having following issues
1. MUX example code uses avformat_alloc_output_context2() to create the
output context for example for .mpg it will choose MPEG1 encoder, the .mpg
file i used is encoded using MPEG2 encoder.
I was wondering how can i select different encoders, is there any API call
which i can use to re-set the encoder name in the context encoder fails
2. I uses the fmt_ctx from decoder to set the encoder parameters, i try to
memcpy the context (decoder to encoder for the codec) but it fails by
setting the different parameters from fmt_ctx to the c
c->width = fmt_ctx->streams[video_stream_idx]->codec->width;
c->height = fmt_ctx->streams[video_stream_idx]->codec->height;
c->coded_width = fmt_ctx->streams[video_stream_idx]->codec>coded_width;
........................
c->gop_size = fmt_ctx->streams[video_stream_idx]->codec->gop_size;
/* emit one intra frame every twelve frames at most */
c->bit_rate = (fmt_ctx->streams[video_stream_idx]->codec->bit_rate == 0) ?
400000 :
fmt_ctx->streams[video_stream_idx]->codec->bit_rate;
/* i am seting it to 400kbps in case it is set to 0 as i am seeing it for
some stream */
........................
I am seeing different issue
1. GOP Size fmt_ctx most of the time has gop_size = 12 which does not
seems like the case for the original/input stream
2. bit-rate i am getting in the output .mp4 is way higher then the one i
see from the fmt_ctx, it seems like encoded bit-stream is in 50Mbits/sec
where as input .mp4 was 300kbps or 400kbps bit-rate
I am wondering what is the best way to set the encoder context using the
input bitstream
[.mp4, .avi, .mpg etc] files
Please let me know if you are able to figure it out
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/3107#comment:10>
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