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Deal with legacay alsa drivers misreporting available channels.

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This commit is contained in:
Robin Davies
2024-11-02 08:59:24 -04:00
parent fc26e47a91
commit 54ae9a64ac
11 changed files with 267 additions and 91 deletions
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src/AlsaDriver.cpp
+115 -51
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@@ -24,6 +24,7 @@
#include "pch.h"
#include "util.hpp"
#include "Finally.hpp"
#include <bit>
#include <memory>
#include "ss.hpp"
@@ -66,7 +67,7 @@ namespace pipedal
AudioFormat *formats,
size_t nItems)
{
snd_pcm_hw_params_t* test_params;
snd_pcm_hw_params_t *test_params;
snd_pcm_hw_params_alloca(&test_params);
for (size_t i = 0; i < nItems; ++i)
@@ -197,15 +198,16 @@ namespace pipedal
AudioDriverHost *driverHost = nullptr;
void validate_capture_handle() { // leftover debugging for a buffer overrun :-/
#ifdef DEBUG
void validate_capture_handle()
{ // leftover debugging for a buffer overrun :-/
#ifdef DEBUG
if (snd_pcm_type(captureHandle) != SND_PCM_TYPE_HW)
{
throw std::runtime_error("Capture handle has been overwritten");
}
#endif
#endif
}
public:
AlsaDriverImpl(AudioDriverHost *driverHost)
: driverHost(driverHost)
@@ -377,35 +379,26 @@ namespace pipedal
unsigned int channels_min = 0;
err = snd_pcm_hw_params_get_channels_max(hwParams,
&channels_max);
if (err < 0) {
if (err < 0)
{
AlsaError(SS("Can't get channels_max."));
}
err = snd_pcm_hw_params_get_channels_min(hwParams,
&channels_min);
if (err < 0) {
if (err < 0)
{
AlsaError(SS("Can't get channels_min."));
}
*channels = channels_max;
if (channels_max > 2 && channels_min <= 2 && channels_min > 0) {
unsigned int bestChannelConfig = 2;
snd_pcm_hw_params_t* test_params;
snd_pcm_hw_params_alloca(&test_params);
snd_pcm_hw_params_copy(test_params, hwParams);
if ((err = snd_pcm_hw_params_set_channels(handle, test_params,
bestChannelConfig)) >= 0)
{
*channels = bestChannelConfig;
}
if (ShouldForceStereoChannels(handle, hwParams, channels_min, channels_max))
{
*channels = 2;
}
if (*channels > 1024)
if (*channels >= 1024)
{
// The default PCM device has unlimited channels.
// report 2 channels
@@ -1312,7 +1305,6 @@ namespace pipedal
}
}
validate_capture_handle();
}
void recover_from_output_underrun(snd_pcm_t *capture_handle, snd_pcm_t *playback_handle, int err)
{
@@ -1398,7 +1390,6 @@ namespace pipedal
}
audioRunning = true;
validate_capture_handle();
}
else
{
@@ -1427,7 +1418,6 @@ namespace pipedal
// buffer boundaries (but discard them)
snd_pcm_sframes_t framesRead;
auto state = snd_pcm_state(handle);
auto frame_bytes = this->captureFrameSize;
do
@@ -1971,12 +1961,14 @@ namespace pipedal
for (size_t i = 0; i < devices.size(); ++i)
{
try {
try
{
const auto &device = devices[i];
auto midiDevice = std::make_unique<AlsaMidiDeviceImpl>();
midiDevice->Open(device);
midiDevices.push_back(std::move(midiDevice));
} catch (const std::exception &e)
}
catch (const std::exception &e)
{
Lv2Log::error(e.what());
}
@@ -2051,6 +2043,95 @@ namespace pipedal
return new AlsaDriverImpl(driverHost);
}
bool ShouldForceStereoChannels(snd_pcm_t *pcmHandle, snd_pcm_hw_params_t *hwParams, unsigned int channelsMin, unsigned int channelsMax)
{
// The problem: old IC2 drivers seem to return 1-8 channels, but 8 channels is non-functinal. The assumption is that legacy drivers
// (I2C drivers, particularl, but also the Rpi headphones device, as an interesting example) that don't support channel maps do this.
// Hypothetically, devices could allow slection of hardware-downmixed surround channels. So deal with this case defensively.
// The approach: check the channel map and do our best to interpret what we find.
// No channel map, or any part of the channel map is unknown? Probably the legalcy case we're interested in. Return TRUE
// If the channel map is a surround format, return true in that case as well.
// If the channel map is pairwise, return false! (legitimately multi-channel devices should not be forced to stereo).
// If the channel map is all FL/FR/MONO return false (a hypothetical configuration for a multi-channel device)
// If the channel map is not all FL/FR/MONO, assume that it's an upmixed/downmixed surround format, and return TRUE.
// This is high-risk code, because it attempts to anticipate hypothetical device configurations with no actual testing.
if (channelsMax <= 2)
return false;
if (channelsMin == channelsMax)
return false;
if (channelsMin > 2)
return false; // can't imagine what sort of device this is.
snd_pcm_hw_params_t *test_params;
snd_pcm_hw_params_alloca(&test_params);
snd_pcm_hw_params_copy(test_params, hwParams);
// can we select 2 channels?
if (snd_pcm_hw_params_set_channels(pcmHandle, test_params, (unsigned int)2) >= 0)
{
snd_pcm_chmap_query_t **chmaps = snd_pcm_query_chmaps(pcmHandle);
if (chmaps == nullptr)
{
return true; // probably an old driver. Do it.
}
Finally ff([chmaps]()
{ snd_pcm_free_chmaps(chmaps); });
for (size_t i = 0; chmaps[i] != nullptr; ++i)
{
snd_pcm_chmap_query_t *chmap = chmaps[i];
if (chmap->map.channels == channelsMax)
{
switch (chmap->type)
{
case SND_CHMAP_TYPE_NONE:
default:
return true; // weird legacy case? Do it.
case SND_CHMAP_TYPE_PAIRED:
return false; // A legitimate multi-channel device. definitely don't do it.
case SND_CHMAP_TYPE_VAR:
case SND_CHMAP_TYPE_FIXED:
{
// we should do it for surround formats. guard against other hypothetical mappings for legitimately multi-channel devices.
snd_pcm_chmap_position pos0 = (snd_pcm_chmap_position)(chmap->map.pos[0]);
if (pos0 == snd_pcm_chmap_position::SND_CHMAP_MONO) // hypothetical channel map of all mono channesl.
{
return false; // don't do it.
}
if (pos0 != snd_pcm_chmap_position::SND_CHMAP_FL && pos0 != snd_pcm_chmap_position::SND_CHMAP_FL) // surround formats always start with FL. Hypothetical quad formats could start with FC.
{
return false; // don't do it.
}
// accept a hypothetical channel map of mixed FL's and FR's, FC's and MONOs. (Multi-channel with mixed mono and stereo pairs).
// But otherwise assume it's a surround map, and use a stereo channel configuration instead.
for (size_t i = 0; i < chmap->map.channels; ++i)
{
snd_pcm_chmap_position pos = (snd_pcm_chmap_position)(chmap->map.pos[i]);
switch (pos)
{
case snd_pcm_chmap_position::SND_CHMAP_MONO:
case snd_pcm_chmap_position::SND_CHMAP_FL:
case snd_pcm_chmap_position::SND_CHMAP_FR:
case snd_pcm_chmap_position::SND_CHMAP_FC:
break; // keep going.
default:
return true; // probably a surround sound map.
}
}
return false;
};
}
}
}
return true; // no matching channel map(!??). nonsensical case. may as well use the stereo config, which might be more sensible.
}
return false;
}
bool GetAlsaChannels(const JackServerSettings &jackServerSettings,
std::vector<std::string> &inputAudioPorts,
std::vector<std::string> &outputAudioPorts)
@@ -2058,7 +2139,7 @@ namespace pipedal
if (jackServerSettings.IsDummyAudioDevice())
{
auto nChannels = GetDummyAudioChannels(jackServerSettings.GetAlsaInputDevice());
inputAudioPorts.clear();
outputAudioPorts.clear();
for (uint32_t i = 0; i < nChannels; ++i)
@@ -2149,17 +2230,9 @@ namespace pipedal
{
throw PiPedalLogicException("No outut channels.");
}
if (playbackChannels > 2 && channelsMin <=2 && channelsMin > 0)
if (ShouldForceStereoChannels(playbackHandle, playbackHwParams, channelsMin, playbackChannels))
{
snd_pcm_hw_params_t* test_params;
snd_pcm_hw_params_alloca(&test_params);
snd_pcm_hw_params_copy(test_params, playbackHwParams);
if (snd_pcm_hw_params_set_channels(playbackHandle,test_params,(unsigned int)2) >= 0)
{
playbackChannels = 2;
}
playbackChannels = 2;
}
err = snd_pcm_hw_params_get_channels_max(captureHwParams, &captureChannels);
@@ -2167,22 +2240,13 @@ namespace pipedal
{
throw PiPedalLogicException("No input channels.");
}
err = snd_pcm_hw_params_get_channels_min(captureHwParams,&channelsMin);
err = snd_pcm_hw_params_get_channels_min(captureHwParams, &channelsMin);
if (err >= 0)
{
if (captureChannels > 2 && channelsMin <= 2 && channelsMin > 0)
if (ShouldForceStereoChannels(captureHandle, captureHwParams, channelsMin, captureChannels))
{
snd_pcm_hw_params_t* test_params;
snd_pcm_hw_params_alloca(&test_params);
snd_pcm_hw_params_copy(test_params, captureHwParams);
if (snd_pcm_hw_params_set_channels(captureHandle,test_params,(unsigned int)2) >= 0)
{
captureChannels = 2;
}
}
captureChannels = 2;
}
}
inputAudioPorts.clear();