[FFmpeg-devel] [PATCH v3] avformat/smoothstreamingenc:add bitrate calculate

[Jun Li]

On Thu, Mar 14, 2019 at 11:22 AM Jun Li <junli1026 at gmail.com> wrote:

> Calculate bitrate based on fragment size, only applied when
> bitrate is not set, for example rtsp source.
>
> Signed-off-by: Jun Li <junli1026 at gmail.com>
> ---
>  libavformat/smoothstreamingenc.c | 32 +++++++++++++++++++++++++++-----
>  1 file changed, 27 insertions(+), 5 deletions(-)
>
> diff --git a/libavformat/smoothstreamingenc.c
> b/libavformat/smoothstreamingenc.c
> index 094712af27..30bb188aa2 100644
> --- a/libavformat/smoothstreamingenc.c
> +++ b/libavformat/smoothstreamingenc.c
> @@ -320,11 +320,13 @@ static int ism_write_header(AVFormatContext *s)
>          AVDictionary *opts = NULL;
>
>          if (!s->streams[i]->codecpar->bit_rate) {
> -            av_log(s, AV_LOG_ERROR, "No bit rate set for stream %d\n", i);
> -            ret = AVERROR(EINVAL);
> -            goto fail;
> +            av_log(s, AV_LOG_WARNING, "No bit rate set for stream %d\n",
> i);
> +            // create a tmp name for the directory of fragments
> +            snprintf(os->dirname, sizeof(os->dirname),
> "%s/QualityLevels(Tmp_%"PRId64")", s->url, i);
> +        } else {
> +            snprintf(os->dirname, sizeof(os->dirname),
> "%s/QualityLevels(%"PRId64")", s->url, s->streams[i]->codecpar->bit_rate);
>          }
> -        snprintf(os->dirname, sizeof(os->dirname),
> "%s/QualityLevels(%"PRId64")", s->url, s->streams[i]->codecpar->bit_rate);
> +
>          if (mkdir(os->dirname, 0777) == -1 && errno != EEXIST) {
>              ret = AVERROR(errno);
>              av_log(s, AV_LOG_ERROR, "mkdir failed\n");
> @@ -519,7 +521,7 @@ static int ism_flush(AVFormatContext *s, int final)
>
>      for (i = 0; i < s->nb_streams; i++) {
>          OutputStream *os = &c->streams[i];
> -        char filename[1024], target_filename[1024], header_filename[1024];
> +        char filename[1024], target_filename[1024],
> header_filename[1024], curr_dirname[1024];
>          int64_t size;
>          int64_t start_ts, duration, moof_size;
>          if (!os->packets_written)
> @@ -541,6 +543,26 @@ static int ism_flush(AVFormatContext *s, int final)
>          size = os->tail_pos - os->cur_start_pos;
>          if ((ret = parse_fragment(s, filename, &start_ts, &duration,
> &moof_size, size)) < 0)
>              break;
> +
> +        if (!s->streams[i]->codecpar->bit_rate) {
> +            int64_t bitrate = (int64_t) size * 8 * AV_TIME_BASE /
> av_rescale_q(duration, s->streams[i]->time_base, AV_TIME_BASE_Q);
> +            if (!bitrate) {
> +                av_log(s, AV_LOG_ERROR, "calculating bitrate get zero.");
> +                ret = AVERROR(EINVAL);
> +                return ret;
> +            }
> +
> +            av_log(s, AV_LOG_WARNING, "calculated bitrate: %ld\n",
> bitrate);
> +            s->streams[i]->codecpar->bit_rate = bitrate;
> +            memcpy(curr_dirname, os->dirname, sizeof(os->dirname));
> +            snprintf(os->dirname, sizeof(os->dirname),
> "%s/QualityLevels(%"PRId64")", s->url, s->streams[i]->codecpar->bit_rate);
> +            snprintf(filename, sizeof(filename), "%s/temp", os->dirname);
> +
> +            // rename the tmp folder back to the correct name since we
> now have the bitrate
> +            if ((ret = ff_rename((const char*)curr_dirname,  os->dirname,
> s)) < 0)
> +                return ret;
> +        }
> +
>          snprintf(header_filename, sizeof(header_filename),
> "%s/FragmentInfo(%s=%"PRIu64")", os->dirname, os->stream_type_tag,
> start_ts);
>          snprintf(target_filename, sizeof(target_filename),
> "%s/Fragments(%s=%"PRIu64")", os->dirname, os->stream_type_tag, start_ts);
>          copy_moof(s, filename, header_filename, moof_size);
> --
> 2.17.1



Ping.
Some information about this patch, I met this bit-rate zero issue when
trying to saving RTSP to Smooth. The current behavior is to exit with
EINVAL if bit-rate is not set. Dash muxer overcome this by calculating from
first fragment size:
https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/dashenc.c#L1545

Since smooth and dash share many common, the patch follows the same path to
solve the issue.  Could someone please take a review ? Thanks.

Best Regards,
-Jun