[FFmpeg-devel] [PATCH v2] lavf/dashenc: Write media trailers when DASH trailer is written.

[Jeyapal, Karthick]

On 11/29/18 11:58 PM, Andrey Semashev wrote:
> This commit ensures that all (potentially, long) filesystem activity is
> performed when the user calls av_write_trailer on the DASH libavformat
> context, not when freeing the context. Also, this defers media segment
> deletion until after the media trailers are written.
> ---
>  libavformat/dashenc.c | 82 ++++++++++++++++++++++++++++++-------------
>  1 file changed, 58 insertions(+), 24 deletions(-)
>
> diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
> index 6ce70e0076..ecfd84a32c 100644
> --- a/libavformat/dashenc.c
> +++ b/libavformat/dashenc.c
> @@ -424,8 +424,6 @@ static void dash_free(AVFormatContext *s)
>          return;
>      for (i = 0; i < s->nb_streams; i++) {
>          OutputStream *os = &c->streams[i];
> -        if (os->ctx && os->ctx_inited)
> -            av_write_trailer(os->ctx);
>          if (os->ctx && os->ctx->pb)
>              ffio_free_dyn_buf(&os->ctx->pb);
>          ff_format_io_close(s, &os->out);
> @@ -1331,6 +1329,47 @@ static void dashenc_delete_file(AVFormatContext *s, char *filename) {
>      }
>  }
>  
> +static int dashenc_delete_segment_file(AVFormatContext *s, const char* file)
> +{
> +    DASHContext *c = s->priv_data;
> +    size_t dirname_len, file_len;
> +    char filename[1024];
> +
> +    dirname_len = strlen(c->dirname);
> +    if (dirname_len >= sizeof(filename)) {
> +        av_log(s, AV_LOG_WARNING, "Cannot delete segments as the directory path is too long: %"PRIu64" characters: %s\n",
> +            (uint64_t)dirname_len, c->dirname);
> +        return AVERROR(ENAMETOOLONG);
> +    }
> +
> +    memcpy(filename, c->dirname, dirname_len);
> +
> +    file_len = strlen(file);
> +    if ((dirname_len + file_len) >= sizeof(filename)) {
> +        av_log(s, AV_LOG_WARNING, "Cannot delete segments as the path is too long: %"PRIu64" characters: %s%s\n",
> +            (uint64_t)(dirname_len + file_len), c->dirname, file);
> +        return AVERROR(ENAMETOOLONG);
> +    }
> +
> +    memcpy(filename + dirname_len, file, file_len + 1); // include the terminating zero
> +    dashenc_delete_file(s, filename);
> +
> +    return 0;
> +}
> +
> +static inline void dashenc_delete_media_segments(AVFormatContext *s, OutputStream *os, int remove_count)
> +{
> +    for (int i = 0; i < remove_count; ++i) {
> +        dashenc_delete_segment_file(s, os->segments[i]->file);
> +
> +        // Delete the segment regardless of whether the file was successfully deleted
> +        av_free(os->segments[i]);
> +    }
> +
> +    os->nb_segments -= remove_count;
> +    memmove(os->segments, os->segments + remove_count, os->nb_segments * sizeof(*os->segments));
> +}
> +
>  static int dash_flush(AVFormatContext *s, int final, int stream)
>  {
>      DASHContext *c = s->priv_data;
> @@ -1420,23 +1459,12 @@ static int dash_flush(AVFormatContext *s, int final, int stream)
>          os->pos += range_length;
>      }
>  
> -    if (c->window_size || (final && c->remove_at_exit)) {
> +    if (c->window_size) {
>          for (i = 0; i < s->nb_streams; i++) {
>              OutputStream *os = &c->streams[i];
> -            int j;
> -            int remove = os->nb_segments - c->window_size - c->extra_window_size;
> -            if (final && c->remove_at_exit)
> -                remove = os->nb_segments;
> -            if (remove > 0) {
> -                for (j = 0; j < remove; j++) {
> -                    char filename[1024];
> -                    snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->segments[j]->file);
> -                    dashenc_delete_file(s, filename);
> -                    av_free(os->segments[j]);
> -                }
> -                os->nb_segments -= remove;
> -                memmove(os->segments, os->segments + remove, os->nb_segments * sizeof(*os->segments));
> -            }
> +            int remove_count = os->nb_segments - c->window_size - c->extra_window_size;
> +            if (remove_count > 0)
> +                dashenc_delete_media_segments(s, os, remove_count);
>          }
>      }
>  
> @@ -1584,6 +1612,7 @@ static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
>  static int dash_write_trailer(AVFormatContext *s)
>  {
>      DASHContext *c = s->priv_data;
> +    int i;
>  
>      if (s->nb_streams > 0) {
>          OutputStream *os = &c->streams[0];
> @@ -1599,14 +1628,19 @@ static int dash_write_trailer(AVFormatContext *s)
>      }
>      dash_flush(s, 1, -1);
>  
> -    if (c->remove_at_exit) {
> -        char filename[1024];
> -        int i;
> -        for (i = 0; i < s->nb_streams; i++) {
> -            OutputStream *os = &c->streams[i];
> -            snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
> -            dashenc_delete_file(s, filename);
> +    for (i = 0; i < s->nb_streams; ++i) {
> +        OutputStream *os = &c->streams[i];
> +        if (os->ctx && os->ctx_inited) {
> +            av_write_trailer(os->ctx);
> +        }
> +
> +        if (c->remove_at_exit) {
> +            dashenc_delete_media_segments(s, os, os->nb_segments);
> +            dashenc_delete_segment_file(s, os->initfile);
>          }
> +    }
> +
> +    if (c->remove_at_exit) {
>          dashenc_delete_file(s, s->url);
>      }
>  
LGTM

Regards,
Karthick