[FFmpeg-devel] [PATCH v3] avcodec/libopus: support disabling phase inversion.

[Menno de Gier]

On Fri, Jan 26, 2018 at 11:30 AM, Menno de Gier <mrdegier at gmail.com> wrote:

> From: Menno <mrdegier at gmail.com>
>
> This supports disabling phase inversion in both the libopus encoder and the
> decoder.
>
> Signed-off-by: Menno <mrdegier at gmail.com>
> ---
>  doc/encoders.texi       |  5 +++++
>  libavcodec/libopusdec.c | 33 +++++++++++++++++++++++++++++++++
>  libavcodec/libopusenc.c | 14 ++++++++++++++
>  3 files changed, 52 insertions(+)
>
> diff --git a/doc/encoders.texi b/doc/encoders.texi
> index 6a410a8cb6..c5dfc646d9 100644
> --- a/doc/encoders.texi
> +++ b/doc/encoders.texi
> @@ -981,6 +981,11 @@ Other values include 0 for mono and stereo, 1 for
> surround sound with masking
>  and LFE bandwidth optimizations, and 255 for independent streams with an
>  unspecified channel layout.
>
> + at item apply_phase_inv (N.A.) (requires libopus >= 1.2)
> +If set to 0, disables the use of phase inversion for intensity stereo,
> +improving the quality of mono downmixes, but slightly reducing normal
> stereo
> +quality. The default is 1 (phase inversion enabled).
> +
>  @end table
>
>  @anchor{libshine}
> diff --git a/libavcodec/libopusdec.c b/libavcodec/libopusdec.c
> index 4f7f4755c2..f82ae57e54 100644
> --- a/libavcodec/libopusdec.c
> +++ b/libavcodec/libopusdec.c
> @@ -25,6 +25,7 @@
>  #include "libavutil/internal.h"
>  #include "libavutil/intreadwrite.h"
>  #include "libavutil/ffmath.h"
> +#include "libavutil/opt.h"
>
>  #include "avcodec.h"
>  #include "internal.h"
> @@ -33,11 +34,15 @@
>  #include "libopus.h"
>
>  struct libopus_context {
> +    AVClass *class;
>      OpusMSDecoder *dec;
>      int pre_skip;
>  #ifndef OPUS_SET_GAIN
>      union { int i; double d; } gain;
>  #endif
> +#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
> +    int apply_phase_inv;
> +#endif
>  };
>
>  #define OPUS_HEAD_SIZE 19
> @@ -136,6 +141,15 @@ static av_cold int libopus_decode_init(AVCodecContext
> *avc)
>      }
>  #endif
>
> +#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
> +    ret = opus_multistream_decoder_ctl(opus->dec,
> +                                       OPUS_SET_PHASE_INVERSION_
> DISABLED(!opus->apply_phase_inv));
> +    if (ret != OPUS_OK)
> +        av_log(avc, AV_LOG_WARNING,
> +               "Unable to set phase inversion: %s\n",
> +               opus_strerror(ret));
> +#endif
> +
>      /* Decoder delay (in samples) at 48kHz */
>      avc->delay = avc->internal->skip_samples = opus->pre_skip;
>
> @@ -209,6 +223,24 @@ static void libopus_flush(AVCodecContext *avc)
>      avc->internal->skip_samples = opus->pre_skip;
>  }
>
> +
> +#define OFFSET(x) offsetof(struct libopus_context, x)
> +#define FLAGS AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
> +static const AVOption libopusdec_options[] = {
> +#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
> +    { "apply_phase_inv", "Apply intensity stereo phase inversion",
> OFFSET(apply_phase_inv), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
> +    { NULL },
> +#endif
> +};
> +
> +static const AVClass libopusdec_class = {
> +    .class_name = "libopusdec",
> +    .item_name  = av_default_item_name,
> +    .option     = libopusdec_options,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
> +
>  AVCodec ff_libopus_decoder = {
>      .name           = "libopus",
>      .long_name      = NULL_IF_CONFIG_SMALL("libopus Opus"),
> @@ -223,5 +255,6 @@ AVCodec ff_libopus_decoder = {
>      .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLT,
>                                                       AV_SAMPLE_FMT_S16,
>                                                       AV_SAMPLE_FMT_NONE },
> +    .priv_class     = &libopusdec_class,
>      .wrapper_name   = "libopus",
>  };
> diff --git a/libavcodec/libopusenc.c b/libavcodec/libopusenc.c
> index b449497d15..4ae81b0bb2 100644
> --- a/libavcodec/libopusenc.c
> +++ b/libavcodec/libopusenc.c
> @@ -39,6 +39,9 @@ typedef struct LibopusEncOpts {
>      int packet_size;
>      int max_bandwidth;
>      int mapping_family;
> +#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
> +    int apply_phase_inv;
> +#endif
>  } LibopusEncOpts;
>
>  typedef struct LibopusEncContext {
> @@ -154,6 +157,14 @@ static int libopus_configure_encoder(AVCodecContext
> *avctx, OpusMSEncoder *enc,
>                     "Unable to set maximum bandwidth: %s\n",
> opus_strerror(ret));
>      }
>
> +#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
> +    ret = opus_multistream_encoder_ctl(enc,
> +                                       OPUS_SET_PHASE_INVERSION_
> DISABLED(!opts->apply_phase_inv));
> +    if (ret != OPUS_OK)
> +        av_log(avctx, AV_LOG_WARNING,
> +               "Unable to set phase inversion: %s\n",
> +               opus_strerror(ret));
> +#endif
>      return OPUS_OK;
>  }
>
> @@ -530,6 +541,9 @@ static const AVOption libopus_options[] = {
>          { "on",             "Use variable bit rate", 0,
> AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, FLAGS, "vbr" },
>          { "constrained",    "Use constrained VBR",   0,
> AV_OPT_TYPE_CONST, { .i64 = 2 }, 0, 0, FLAGS, "vbr" },
>      { "mapping_family", "Channel Mapping Family",
> OFFSET(mapping_family), AV_OPT_TYPE_INT,   { .i64 = -1 },   -1,  255,
> FLAGS, "mapping_family" },
> +#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
> +    { "apply_phase_inv", "Apply intensity stereo phase inversion",
> OFFSET(apply_phase_inv), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
> +#endif
>      { NULL },
>  };
>
> --
> 2.16.1
>
>
Did anyone get a chance to look at this? Happy to make changes if needed of
course.

-Menno