[FFmpeg-devel] [PATCH] libavformat/keyframes: output keyframe indexes

[Michael Niedermayer]

On Mon, May 04, 2015 at 02:35:45AM +1200, Jonathan Viney wrote:
> Hi,
> 
> First patch here. I wrote this format to be able to get the keyframe
> indexes faster than seemed possible with ffprobe, and also to get more
> familiar with ffmpeg.
> 
> ffmpeg -i input.mkv -c copy -f keyframes -keyframes_filename keyframes.txt
> /dev/null
> 
> Could something like this be included in ffmpeg? Or is this already
> achievable with the current code?

iam a bit undecided if this is a good idea but

why is this faster than ffprobe ? or rather why is ffprobe slow ?

[...]
> +
> +#include "avformat.h"
> +#include "libavutil/opt.h"
> +
> +typedef struct {
> +    const AVClass *class;
> +    int frame_count;
> +    char *filename;
> +    FILE *file;
> +} KeyFramesContext;
> +
> +av_cold static int kf_init(AVFormatContext *s)
> +{
> +    KeyFramesContext *kf = s->priv_data;
> +
> +    kf->file = fopen(kf->filename, "w");

this should use the io context like any other muxer not bypass it
with fopen/f*...


> +
> +    if (kf->file) {
> +        av_log(s, AV_LOG_ERROR, "failed opening key frames file: %s\n",
> kf->filename);
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int kf_write_packet(struct AVFormatContext *s, AVPacket *pkt)
> +{
> +    KeyFramesContext *kf = s->priv_data;
> +
> +    if (pkt->flags & AV_PKT_FLAG_KEY) {
> +        av_log(s, AV_LOG_DEBUG, "key frame at index %d\n",
> kf->frame_count);

patch is corrupted by linebreaks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
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