[FFmpeg-devel] [PATCH 2/3] Add a new hls_flag peak_segment_bw

[Jeyapal, Karthick]

On 2/12/18 2:24 PM, Amit Kale wrote:
> If this flag is set, BANDWIDTH value in a master playlist entry will be set to
> the peak segment bandwidth.
Thanks for sending the patch. Here are some comments.
> ---
>  doc/muxers.texi      |  4 ++++
>  libavformat/hlsenc.c | 29 +++++++++++++++++++++--------
>  2 files changed, 25 insertions(+), 8 deletions(-)
>
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index d9a5cc03dc..e2c9cbfa2f 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -741,6 +741,10 @@ subdirectories.
>  Possible values:
>
>  @table @samp
> + at item peak_segment_bw
> +If this flag is set, BANDWIDTH value in a master playlist entry will be
> +set to the peak segment bandwidth.
> +
>  @item single_file
>  If this flag is set, the muxer will store all segments in a single MPEG-TS
>  file, and will use byte ranges in the playlist. HLS playlists generated with
> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
> index 9970c4c575..f40cd0b98f 100644
> --- a/libavformat/hlsenc.c
> +++ b/libavformat/hlsenc.c
> @@ -98,6 +98,7 @@ typedef enum HLSFlags {
>      HLS_TEMP_FILE = (1 << 11),
>      HLS_PERIODIC_REKEY = (1 << 12),
>      HLS_INDEPENDENT_SEGMENTS = (1 << 13),
> +    HLS_PEAK_SEGMENT_BW = (1 << 14),
Also set the version number as 7 when this flag is set. Maybe in hls_window.
Maybe something like
    if (hls->flags & HLS_PEAK_SEGMENT_BW) {
        hls->version = 7;
    }
>  } HLSFlags;
>
>  typedef enum {
> @@ -1168,7 +1169,8 @@ static int get_relative_url(const char *master_url, const char *media_url,
>  }
>
>  static int create_master_playlist(AVFormatContext *s,
> -                                  VariantStream * const input_vs)
> +                                  VariantStream * const input_vs,
> +                                  int last)
>  {
>      HLSContext *hls = s->priv_data;
>      VariantStream *vs, *temp_vs;
> @@ -1185,7 +1187,7 @@ static int create_master_playlist(AVFormatContext *s,
>          for (i = 0; i < hls->nb_varstreams; i++)
>              if (!hls->var_streams[i].m3u8_created)
>                  return 0;
> -    } else {
> +    } else if (!last) {
>           /* Keep publishing the master playlist at the configured rate */
>          if (&hls->var_streams[0] != input_vs || !hls->master_publish_rate ||
>              input_vs->number % hls->master_publish_rate)
> @@ -1292,11 +1294,21 @@ static int create_master_playlist(AVFormatContext *s,
>          }
>
>          bandwidth = 0;
> -        if (vid_st)
> -            bandwidth += vid_st->codecpar->bit_rate;
> -        if (aud_st)
> -            bandwidth += aud_st->codecpar->bit_rate;
> -        bandwidth += bandwidth / 10;
> +        if (last && hls->flags & HLS_PEAK_SEGMENT_BW) {
> +            HLSSegment *hs = vs->segments;
> +            while (hs) {
> +                int64_t segment_bandwidth = hs->size * 8 / hs->duration;
> +                if (bandwidth < segment_bandwidth)
> +                    bandwidth = segment_bandwidth;
> +                hs = hs->next;
> +            }
I guess, this may not work in case AV streams as separate renditions.
In such a case, only video’s peak bitrate is getting calculated here. 
Audio stream’s peak bandwidth is missed out. Please correct me, if I am wrong here.
> +        } else {
> +            if (vid_st)
> +                bandwidth += vid_st->codecpar->bit_rate;
> +            if (aud_st)
> +                bandwidth += aud_st->codecpar->bit_rate;
> +            bandwidth += bandwidth / 10;
> +        }
>
>          ccgroup = NULL;
>          if (vid_st && vs->ccgroup) {
> @@ -1437,7 +1449,7 @@ fail:
>          ff_rename(temp_filename, vs->m3u8_name, s);
>
>      if (ret >= 0 && hls->master_pl_name)
> -        if (create_master_playlist(s, vs) < 0)
> +        if (create_master_playlist(s, vs, last) < 0)
>              av_log(s, AV_LOG_WARNING, "Master playlist creation failed\n");
>
>      return ret;
> @@ -2753,6 +2765,7 @@ static const AVOption options[] = {
>      {"fmp4",   "make segment file to fragment mp4 files in m3u8", 0, AV_OPT_TYPE_CONST, {.i64 = SEGMENT_TYPE_FMP4 }, 0, UINT_MAX, E, "segment_type"},
>      {"hls_fmp4_init_filename", "set fragment mp4 file init filename", OFFSET(fmp4_init_filename),   AV_OPT_TYPE_STRING, {.str = "init.mp4"},            0,       0,         E},
>      {"hls_flags",     "set flags affecting HLS playlist and media file generation", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = 0 }, 0, UINT_MAX, E, "flags"},
> +    {"peak_segment_bw",   "sets bandwidth in master play list to peak segment bandwidth", 0, AV_OPT_TYPE_CONST, {.i64 = HLS_PEAK_SEGMENT_BW }, 0, UINT_MAX,   E, "flags"},
>      {"single_file",   "generate a single media file indexed with byte ranges", 0, AV_OPT_TYPE_CONST, {.i64 = HLS_SINGLE_FILE }, 0, UINT_MAX,   E, "flags"},
>      {"temp_file", "write segment to temporary file and rename when complete", 0, AV_OPT_TYPE_CONST, {.i64 = HLS_TEMP_FILE }, 0, UINT_MAX,   E, "flags"},
>      {"delete_segments", "delete segment files that are no longer part of the playlist", 0, AV_OPT_TYPE_CONST, {.i64 = HLS_DELETE_SEGMENTS }, 0, UINT_MAX,   E, "flags"},