[vlc-devel] [PATCH v2 3/7] aout: add gapless support

Rémi Denis-Courmont remi at remlab.net
Thu Mar 21 14:28:53 CET 2019


No. You are making unwarranted assumptions, and not just about no audio ES. I cannot agree.

Le 21 mars 2019 20:49:49 GMT+08:00, Thomas Guillem <thomas at gllm.fr> a écrit :
>
>On Thu, Mar 21, 2019, at 13:42, Rémi Denis-Courmont wrote:
>> I already told you that this cannot work. If you think about all
>possible combos, it's kinda obvious that concurrent inputs are
>necessary, but not sufficient, to make it work.
>
>Not obvious at all. It works for most common case: playing local or
>network music album. The buffer of the audio output is generally around
>500ms before a drain, this leave a *lot* of time to open the next
>input. I can even play a music cut into several 200ms pieces without
>any problem.
>And for the case where the audio buffer size is not enough ? It's
>handled: gapless will be canceled (drain/flush last stream and open the
>new one).
>
>> 
>> You cannot know if PTS will be continuous or if the formats will
>match, or if there will be an active audio ES at all.
>
>My current branch handle the case when PTS are not continuous or if
>format won't match.
>
>Only your last point is not handled. This last point need to have
>concurrent input: activate gapless only if the next media is sure to
>have an active audio ES.
>
>> 
>> Le 21 mars 2019 01:09:10 GMT+08:00, Thomas Guillem <thomas at gllm.fr> a
>écrit :
>>> The player will call aout_OutputSetGaplessEnabled(true|false) when
>there is a
>>> next media to play or not. This call is protected with the same
>mutex used for
>>> start/stop and can be called from anywhere.
>>> 
>>> Then, when the stream is draining (aout_DecDrain), it will postpone
>the actual
>>> drain if gapless is enabled, and do the following depending on the
>next aout
>>> call:
>>> 
>>>  - if play is called just after, the postponed drain is executed and
>the
>>>    gapless state is canceled.
>>>  - if flush is called, the gapless state is canceled and everything
>is flushed
>>>  - if stop is called, filters are cleaned but the stream is not
>stopped, it is
>>>    saved for a future usage: (via aout_OutputSaveStream()).
>>> 
>>> On the next stream start, it will try to recover the previous stream
>(that
>>> could be stopped if the player disabled gapless in the meantime) and
>will do
>>> the following depending on the aout_DecNew parameters:
>>> 
>>>  - if format are different: cancel gapless state, drain, flush and
>stop the
>>>    previous stream.
>>> 
>>>  - if format are equals: use the previous stream (don't call
>aout->stop(),
>>>    aout->start()), and set-up new filters chain with the new clock.
>>> 
>>> The final gapless transition will be done from aout_DecPlay():
>>> 
>>>  - if the previous stream delay (time_get) is compatible with the
>next clock,
>>>    blocks will be added in a temporary buffer until the clock jitter
>delay is
>>>    reached.
>>>  - if not, cancel the gapless state, drain and flush the
>(previous=current)
>>>    stream (but don't restart it), and play all blocks normally.
>>> 
>>> When the jitter delay is reached, blocks added in the temporary
>buffers can be
>>> played and the playback can resume normally.
>>> 
>>> Fixes #549 src/audio_output/aout_internal.h |  17 +++
>>>  src/audio_output/dec.c           | 206
>+++++++++++++++++++++++++++++--
>>>  src/audio_output/output.c        |  74 +++++++++++
>>>  3 files changed, 289 insertions(+), 8 deletions(-)
>>> 
>>> diff --git a/src/audio_output/aout_internal.h
>b/src/audio_output/aout_internal.h
>>> index 12fa4dfad9..bab59977eb 100644
>>> --- a/src/audio_output/aout_internal.h
>>> +++ b/src/audio_output/aout_internal.h
>>> @@ -47,6 +47,8 @@ typedef struct
>>>      aout_filters_t *filters;
>>>      aout_volume_t *volume;
>>>  
>>> +    bool stream_saved;
>>> +
>>>      struct
>>>      {
>>>          vlc_mutex_t lock;
>>> @@ -85,6 +87,17 @@ typedef struct
>>>      atomic_uint buffers_played;
>>>      atomic_uchar restart;
>>>  
>>> +    bool gapless_enabled;
>>> +    enum
>>> +    {
>>> +        GAPLESS_STATE_NONE,
>>> +        GAPLESS_STATE_DRAINED,
>>> +        GAPLESS_STATE_STOPPED,
>>> +        GAPLESS_STATE_STARTED,
>>> +    } gapless_state;
>>> +    block_t *gapless_block_chain;
>>> +    block_t **gapless_block_last;
>>> +
>>>      atomic_uintptr_t refs;
>>>  } aout_owner_t;
>>>  
>>> @@ -120,6 +133,10 @@ void aout_Destroy (audio_output_t *);
>>>  int aout_OutputNew(audio_output_t *, audio_sample_format_t *,
>>>                     aout_filters_cfg_t *filters_cfg);
>>>  void aout_OutputDelete( audio_output_t * p_aout );
>>> +void aout_OutputSetGaplessEnabled(audio_output_t *aout, bool
>enabled);
>>> +bool aout_OutputIsGaplessEnabled(audio_output_t *aout);
>>> +int aout_OutputRecoverStream(audio_output_t *aout);
>>> +void aout_OutputSaveStream(audio_output_t *aout);
>>>  
>>>  
>>>  /* From common.c : */
>>> diff --git a/src/audio_output/dec.c b/src/audio_output/dec.c
>>> index 75ea4e6621..e4f1737776 100644
>>> --- a/src/audio_output/dec.c
>>> +++ b/src/audio_output/dec.c
>>> @@ -65,6 +65,44 @@ static bool aout_FormatEquals(const
>audio_sample_format_t *f1,
>>>          && f1->i_channels == f2->i_channels;
>>>  }
>>>  
>>> +static int aout_GaplessReuseStream(audio_output_t *aout,
>>> +                                   const audio_sample_format_t
>*format,
>>> +                                   vlc_clock_t *clock,
>>> +                                   const audio_replay_gain_t
>*replay_gain)
>>> +{
>>> +    aout_owner_t *owner = aout_owner(aout);
>>> +
>>> +    if (aout_OutputRecoverStream(aout) != VLC_SUCCESS)
>>> +    {
>>> +        /* Unlikely case: The old stream was already stopped by the
>player */
>>> +        owner->gapless_state = GAPLESS_STATE_NONE;
>>> +        return -1;
>>> +    }
>>> +
>>> +    if (!aout_FormatEquals(format, &owner->input_format))
>>> +        goto fail;
>>> +
>>> +    /* Reuse the previous stream but set-up new clock and filters
>*/
>>> +    owner->sync.clock = clock;
>>> +    owner->filters =
>>> +        aout_FiltersNewWithClock(VLC_OBJECT(aout), clock,
>>> +                                 format, &owner->mixer_format,
>>> +                                 &owner->filters_cfg);
>>> +    if (owner->filters == NULL)
>>> +        goto fail;
>>> +
>>> +    owner->volume = aout_volume_New (aout, replay_gain);
>>> +    owner->gapless_state = GAPLESS_STATE_STARTED;
>>> +    msg_Dbg(aout, "trying gapless transition");
>>> +    return 0;
>>> +fail:
>>> +    /* No gapless: drain and delete the old stream */
>>> +    aout_Drain(aout);
>>> +    aout_OutputDelete(aout);
>>> +    owner->gapless_state = GAPLESS_STATE_NONE;
>>> +    return -1;
>>> +}
>>> +
>>>  /**
>>>   * Creates an audio output
>>>   */
>>> @@ -74,6 +112,16 @@ int aout_DecNew(audio_output_t *p_aout, const
>audio_sample_format_t *p_format,
>>>      assert(p_aout);
>>>      assert(p_format);
>>>      assert(clock);
>>> +
>>> +    aout_owner_t *owner = aout_owner(p_aout);
>>> +
>>> +    assert(owner->gapless_state == GAPLESS_STATE_NONE
>>> +        || owner->gapless_state == GAPLESS_STATE_STOPPED);
>>> +
>>> +    if (owner->gapless_state == GAPLESS_STATE_STOPPED
>>> +     && aout_GaplessReuseStream(p_aout, p_format, clock,
>p_replay_gain) == 0)
>>> +        return 0;
>>> +
>>>      if( p_format->i_bitspersample > 0 )
>>>      {
>>>          /* Sanitize audio format, input need to have a valid
>physical channels
>>> @@ -100,8 +148,6 @@ int aout_DecNew(audio_output_t *p_aout, const
>audio_sample_format_t *p_format,
>>>          return -1;
>>>      }
>>>  
>>> -    aout_owner_t *owner = aout_owner(p_aout);
>>> -
>>>      /* Create the audio output stream */
>>>      owner->volume = aout_volume_New (p_aout, p_replay_gain);
>>>  
>>> @@ -147,11 +193,25 @@ void aout_DecDelete (audio_output_t *aout)
>>>  {
>>>      aout_owner_t *owner = aout_owner (aout);
>>>  
>>> +    assert(owner->gapless_state == GAPLESS_STATE_NONE
>>> +        || owner->gapless_state == GAPLESS_STATE_DRAINED);
>>> +
>>>      if (owner->mixer_format.i_format)
>>>      {
>>> -        aout_DecFlush(aout);
>>> -        aout_FiltersDelete (aout, owner->filters);
>>> -        aout_OutputDelete (aout);
>>> +        if (owner->gapless_state == GAPLESS_STATE_DRAINED)
>>> +        {
>>> +            /* Gapless transition: save the stream for the next
>aout_DecNew
>>> +             * call */
>>> +            aout_OutputSaveStream(aout);
>>> +            owner->gapless_state = GAPLESS_STATE_STOPPED;
>>> +            aout_FiltersDelete (aout, owner->filters);
>>> +        }
>>> +        else
>>> +        {
>>> +            aout_DecFlush(aout);
>>> +            aout_FiltersDelete (aout, owner->filters);
>>> +            aout_OutputDelete (aout);
>>> +        }
>>>      }
>>>      aout_volume_Delete (owner->volume);
>>>      owner->volume = NULL;
>>> @@ -206,6 +266,7 @@ static int aout_CheckReady (audio_output_t
>*aout)
>>>              }
>>>              aout_FiltersSetClockDelay(owner->filters,
>owner->sync.delay);
>>>          }
>>> +        owner->gapless_state = GAPLESS_STATE_NONE;
>>>          /* TODO: This would be a good time to call clean up any
>video output
>>>           * left over by an audio visualization:
>>>          input_resource_TerminatVout(MAGIC HERE); */
>>> @@ -426,6 +487,89 @@ static void aout_Play(audio_output_t *aout,
>block_t *block,
>>>      atomic_fetch_add_explicit(&owner->buffers_played, 1,
>memory_order_relaxed);
>>>  }
>>>  
>>> +static void aout_GaplessPlay(audio_output_t *aout, block_t *block,
>>> +                             vlc_tick_t system_now, vlc_tick_t
>original_pts)
>>> +{
>>> +    aout_owner_t *owner = aout_owner (aout);
>>> +    vlc_tick_t delay;
>>> +
>>> +    assert(owner->gapless_state == GAPLESS_STATE_STARTED);
>>> +
>>> +    /* Save blocks until we reach the new clock jitter delay or
>until we cancel
>>> +     * gapless due to timing issues */
>>> +    if (block != NULL)
>>> +    {
>>> +        block->i_dts = original_pts;
>>> +        block_ChainLastAppend(&owner->gapless_block_last, block);
>>> +    }
>>> +
>>> +    if (aout->time_get(aout, &delay) != 0)
>>> +    {
>>> +        msg_Warn(aout, "aout delay invalid: canceling gapless");
>>> +        goto cancel;
>>> +    }
>>> +
>>> +    const vlc_tick_t play_date =
>>> +        vlc_clock_ConvertToSystem(owner->sync.clock, system_now, 0,
>>> +                                  owner->sync.rate);
>>> +    const vlc_tick_t jitter = play_date - system_now;
>>> +
>>> +    if (delay <= jitter)
>>> +    {
>>> +        msg_Warn(aout, "clock jitter higher than aout delay:
>canceling gapless");
>>> +        goto cancel;
>>> +    }
>>> +
>>> +    if (jitter >= 0 && block != NULL)
>>> +        return; /* need more blocks */
>>> +
>>> +    if (delay <= AOUT_MAX_PTS_ADVANCE)
>>> +    {
>>> +        msg_Warn(aout, "delay too short: canceling gapless");
>>> +        goto cancel;
>>> +    }
>>> +
>>> +    if (owner->gapless_block_chain)
>>> +    {
>>> +        const vlc_tick_t block_original_pts =
>owner->gapless_block_chain->i_dts;
>>> +        const vlc_tick_t drift =
>>> +            vlc_clock_Update(owner->sync.clock, system_now + delay,
>>> +                             block_original_pts, owner->sync.rate);
>>> +        if (drift != 0)
>>> +        {
>>> +            msg_Warn(aout, "can't update clock: canceling
>gapless");
>>> +            goto cancel;
>>> +        }
>>> +    }
>>> +
>>> +    msg_Dbg(aout, "gapless transition successful");
>>> +    owner->gapless_state = GAPLESS_STATE_NONE;
>>> +    owner->sync.discontinuity = false;
>>> +
>>> +cancel:
>>> +    if (owner->gapless_state != GAPLESS_STATE_NONE)
>>> +    {
>>> +        /* Gapless canceled: drain and flush the previous stream */
>>> +        aout_Drain(aout);
>>> +        aout_DecFlush(aout);
>>> +        owner->gapless_state = GAPLESS_STATE_NONE;
>>> +    }
>>> +
>>> +    /* Play every saved blocks now */
>>> +    for (block_t *next = NULL, *it = owner->gapless_block_chain;
>it; it = next)
>>> +    {
>>> +        next = it->p_next;
>>> +        const vlc_tick_t block_original_pts = it->i_dts;
>>> +        it->i_dts = VLC_TICK_INVALID;
>>> +
>>> +        aout_Play(aout, it, system_now, block_original_pts);
>>> +        system_now = vlc_tick_now(); /* system_now might be too old
>*/
>>> +    }
>>> +
>>> +    owner->gapless_block_chain = NULL;
>>> +    owner->gapless_block_last = &owner->gapless_block_chain;
>>> +}
>>> +
>>> 
>/*****************************************************************************
>>>   * aout_DecPlay : filter & mix the decoded buffer
>>>  
>*****************************************************************************/
>>> @@ -433,6 +577,17 @@ int aout_DecPlay(audio_output_t *aout, block_t
>*block)
>>>  {
>>>      aout_owner_t *owner = aout_owner (aout);
>>>  
>>> +    if (unlikely(owner->gapless_state == GAPLESS_STATE_DRAINED))
>>> +    {
>>> +        /* Drained but not stopped: do the drain that was
>previously ignored
>>> +         * and cancel the gapless transition */
>>> +        aout_Drain(aout);
>>> +        owner->gapless_state = GAPLESS_STATE_NONE;
>>> +    }
>>> +
>>> +    assert(owner->gapless_state == GAPLESS_STATE_NONE
>>> +        || owner->gapless_state == GAPLESS_STATE_STARTED);
>>> +
>>>      assert (block->i_pts != VLC_TICK_INVALID);
>>>  
>>>      block->i_length = vlc_tick_from_samples( block->i_nb_samples,
>>> @@ -476,7 +631,8 @@ int aout_DecPlay(audio_output_t *aout, block_t
>*block)
>>>      aout_volume_Amplify (owner->volume, block);
>>>  
>>>      /* Update delay */
>>> -    if (owner->sync.request_delay != owner->sync.delay)
>>> +    if (owner->gapless_state == GAPLESS_STATE_NONE
>>> +     && owner->sync.request_delay != owner->sync.delay)
>>>      {
>>>          owner->sync.delay = owner->sync.request_delay;
>>>          vlc_tick_t delta = vlc_clock_SetDelay(owner->sync.clock,
>owner->sync.delay);
>>> @@ -486,7 +642,12 @@ int aout_DecPlay(audio_output_t *aout, block_t
>*block)
>>>      }
>>>  
>>>      vlc_tick_t system_now = vlc_tick_now();
>>> -    aout_Play(aout, block, system_now, original_pts);
>>> +
>>> +    if (owner->gapless_state == GAPLESS_STATE_STARTED)
>>> +        aout_GaplessPlay(aout, block, system_now, original_pts);
>>> +    else
>>> +        aout_Play(aout, block, system_now, original_pts);
>>> +
>>>      return ret;
>>>  drop:
>>>      owner->sync.discontinuity = true;
>>> @@ -540,6 +701,15 @@ void aout_DecFlush(audio_output_t *aout)
>>>  
>>>      if (owner->mixer_format.i_format)
>>>      {
>>> +        if (owner->gapless_state != GAPLESS_STATE_NONE)
>>> +        {
>>> +            /* Flush gapless buffers and reset state */
>>> +            block_ChainRelease(owner->gapless_block_chain);
>>> +            owner->gapless_block_chain = NULL;
>>> +            owner->gapless_block_last =
>&owner->gapless_block_chain;
>>> +            owner->gapless_state = GAPLESS_STATE_NONE;
>>> +        }
>>> +
>>>          aout_FiltersFlush (owner->filters);
>>>  
>>>          aout->flush(aout);
>>> @@ -571,11 +741,31 @@ void aout_DecDrain(audio_output_t *aout)
>>>      if (!owner->mixer_format.i_format)
>>>          return;
>>>  
>>> +    assert(owner->gapless_state == GAPLESS_STATE_NONE
>>> +        || owner->gapless_state == GAPLESS_STATE_STARTED);
>>> +
>>> +    if (owner->gapless_state == GAPLESS_STATE_STARTED)
>>> +    {
>>> +        /* Drain gapless block chain */
>>> +        aout_GaplessPlay(aout, NULL, vlc_tick_now(),
>VLC_TICK_INVALID);
>>> +    }
>>> +
>>>      block_t *block = aout_FiltersDrain (owner->filters);
>>>      if (block)
>>>          aout->play(aout, block, vlc_tick_now());
>>>  
>>> -    aout_Drain(aout);
>>> +    if (AOUT_FMT_LINEAR(&owner->mixer_format)
>>> +     && aout_OutputIsGaplessEnabled(aout))
>>> +    {
>>> +
>>> +        /* First gapless state, cancellable if stop/play/flush is
>not called
>>> +         * right after */
>>> +        owner->gapless_state = GAPLESS_STATE_DRAINED;
>>> +        owner->gapless_block_chain = NULL;
>>> +        owner->gapless_block_last = &owner->gapless_block_chain;
>>> +    }
>>> +    else
>>> +        aout_Drain(aout);
>>>  
>>>      vlc_clock_Reset(owner->sync.clock);
>>>      aout_FiltersResetClock(owner->filters);
>>> diff --git a/src/audio_output/output.c b/src/audio_output/output.c
>>> index 5c378dbb31..6f11628a52 100644
>>> --- a/src/audio_output/output.c
>>> +++ b/src/audio_output/output.c
>>> @@ -223,6 +223,9 @@ audio_output_t *aout_New (vlc_object_t *parent)
>>>      vlc_viewpoint_init (&owner->vp.value);
>>>      atomic_init (&owner->vp.update, false);
>>>      atomic_init(&owner->refs, 0);
>>> +    owner->stream_saved = false;
>>> +    owner->gapless_enabled = false;
>>> +    owner->gapless_state = GAPLESS_STATE_NONE;
>>>  
>>>      /* Audio output module callbacks */
>>>      var_Create (aout, "volume", VLC_VAR_FLOAT);
>>> @@ -565,6 +568,7 @@ int aout_OutputNew (audio_output_t *aout,
>audio_sample_format_t *restrict fmt,
>>>      aout->current_sink_info.headphones = false;
>>>  
>>>      vlc_mutex_lock(&owner->lock);
>>> +    assert(!owner->stream_saved);
>>>      int ret = aout->start(aout, fmt);
>>>      assert(aout->flush && aout->play && aout->time_get &&
>aout->pause);
>>>      vlc_mutex_unlock(&owner->lock);
>>> @@ -592,10 +596,80 @@ void aout_OutputDelete (audio_output_t *aout)
>>>  {
>>>      aout_owner_t *owner = aout_owner(aout);
>>>      vlc_mutex_lock(&owner->lock);
>>> +    assert(!owner->stream_saved);
>>>      aout->stop (aout);
>>>      vlc_mutex_unlock(&owner->lock);
>>>  }
>>>  
>>> +/**
>>> + * Recover the ownership of the stream previously saved
>>> + */
>>> +int aout_OutputRecoverStream(audio_output_t *aout)
>>> +{
>>> +    aout_owner_t *owner = aout_owner(aout);
>>> +    vlc_mutex_lock(&owner->lock);
>>> +    if (unlikely(!owner->stream_saved))
>>> +    {
>>> +        /* The stream was already stopped by a previous
>>> +         * aout_OutputSetGaplessEnabled(false) from an other thread
>*/
>>> +        vlc_mutex_unlock(&owner->lock);
>>> +        return VLC_EGENERIC;
>>> +    }
>>> +
>>> +    owner->stream_saved = false;
>>> +    vlc_mutex_unlock(&owner->lock);
>>> +
>>> +    return VLC_SUCCESS;
>>> +}
>>> +
>>> +/**
>>> + * Save the stream for a future usage
>>> + */
>>> +void aout_OutputSaveStream(audio_output_t *aout)
>>> +{
>>> +    aout_owner_t *owner = aout_owner(aout);
>>> +
>>> +    vlc_mutex_lock(&owner->lock);
>>> +
>>> +    assert(!owner->stream_saved);
>>> +
>>> +    /* The caller of aout_OutputSetGaplessEnabled (the player) is
>now the owner
>>> +     * of the stream during gapless transition. */
>>> +    owner->stream_saved = true;
>>> +    vlc_mutex_unlock(&owner->lock);
>>> +}
>>> +
>>> +/**
>>> + * Enable or disable gapless
>>> + *
>>> + * Can be called by the player when the next media changes
>>> + */
>>> +void aout_OutputSetGaplessEnabled(audio_output_t *aout, bool
>enabled)
>>> +{
>>> +    aout_owner_t *owner = aout_owner (aout);
>>> +
>>> +    vlc_mutex_lock(&owner->lock);
>>> +
>>> +    owner->gapless_enabled = enabled;
>>> +
>>> +    if (!enabled && unlikely(owner->stream_saved))
>>> +    {
>>> +        aout->stop (aout);
>>> +        owner->stream_saved = false;
>>> +    }
>>> +
>>> +    vlc_mutex_unlock(&owner->lock);
>>> +}
>>> +
>>> +bool aout_OutputIsGaplessEnabled(audio_output_t *aout)
>>> +{
>>> +    aout_owner_t *owner = aout_owner(aout);
>>> +    vlc_mutex_lock(&owner->lock);
>>> +    const bool enabled = owner->gapless_enabled;
>>> +    vlc_mutex_unlock(&owner->lock);
>>> +    return enabled;
>>> +}
>>> +
>>>  /**
>>>   * Gets the volume of the audio output stream (independent of
>mute).
>>>   * \return Current audio volume (0. = silent, 1. = nominal),
>> 
>> -- 
>> Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez
>excuser ma brièveté. 
>> _______________________________________________
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-- 
Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez excuser ma brièveté.
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