[pulseaudio-discuss] [PATCH v2 3/3] resampler: Add support for resamplers that consume less data than asked.
David Henningsson
david.henningsson at canonical.com
Wed Apr 25 23:20:52 PDT 2012
On 04/25/2012 05:35 PM, Tanu Kaskinen wrote:
> libsamplerate_resample() assumed that src_process() would
> always consume the whole input buffer. That was an invalid
> assumption leading to crashes.
>
> This patch adds a leftover memchunk for storing any
> non-consumed input. When pa_resampler_run() is called next
> time, the leftover is prepended to the new input.
Thanks for the patches. I've not gone into great detail about the below,
but I trust your expertise. :-)
Two nitpicks below. The other two patches look good.
>
> Changes in v2:
> - If add_leftover() is called with zero-length input while
> the leftover length is non-zero, we don't try to acquire
> the input memblock.
> - Instead of taking a reference to the original input in
> libsamplerate_resample(), we copy the leftover data to a
> new memblock. This is done, because otherwise, if the
> input is one of the internal buffers, the data can get
> overwritten before reading it in add_leftover().
> - Store add_leftover_buf size in bytes instead of samples
> (more convenient, but less consistent with other code).
>
> BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=47156
> ---
> src/pulsecore/resampler.c | 94 +++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 87 insertions(+), 7 deletions(-)
>
> diff --git a/src/pulsecore/resampler.c b/src/pulsecore/resampler.c
> index 258d1fe..ef014f8 100644
> --- a/src/pulsecore/resampler.c
> +++ b/src/pulsecore/resampler.c
> @@ -58,12 +58,16 @@ struct pa_resampler {
>
> pa_memchunk to_work_format_buf;
> pa_memchunk remap_buf;
> + pa_memchunk add_leftover_buf; /* For concatenating leftover with input. */
> pa_memchunk resample_buf;
> pa_memchunk from_work_format_buf;
> + pa_memchunk leftover_buf; /* For storing the leftover data. */
> unsigned to_work_format_buf_samples;
> unsigned remap_buf_samples;
> + unsigned add_leftover_buf_bytes;
> unsigned resample_buf_samples;
> unsigned from_work_format_buf_samples;
> + unsigned leftover_buf_bytes;
>
> pa_sample_format_t work_format;
>
> @@ -344,10 +348,14 @@ void pa_resampler_free(pa_resampler *r) {
> pa_memblock_unref(r->to_work_format_buf.memblock);
> if (r->remap_buf.memblock)
> pa_memblock_unref(r->remap_buf.memblock);
> + if (r->add_leftover_buf.memblock)
> + pa_memblock_unref(r->add_leftover_buf.memblock);
> if (r->resample_buf.memblock)
> pa_memblock_unref(r->resample_buf.memblock);
> if (r->from_work_format_buf.memblock)
> pa_memblock_unref(r->from_work_format_buf.memblock);
> + if (r->leftover_buf.memblock)
> + pa_memblock_unref(r->leftover_buf.memblock);
>
> pa_xfree(r);
> }
> @@ -379,17 +387,24 @@ void pa_resampler_set_output_rate(pa_resampler *r, uint32_t rate) {
> size_t pa_resampler_request(pa_resampler *r, size_t out_length) {
> pa_assert(r);
>
> - /* Let's round up here */
> -
> + /* Let's round up here to make it more likely that the caller will get at
> + * least out_length amount of data from pa_resampler_run().
> + *
> + * We don't take the leftover into account here. If we did, then it might
> + * be in theory possible that this function would return 0 and
> + * pa_resampler_run() would also return 0. That could lead to infinite
> + * loops. When the leftover is ignored here, such loops would eventually
> + * terminate, because the leftover would grow each round, finally
> + * surpassing the minimum input threshold of the resampler. */
> return (((((out_length + r->o_fz-1) / r->o_fz) * r->i_ss.rate) + r->o_ss.rate-1) / r->o_ss.rate) * r->i_fz;
> }
>
> size_t pa_resampler_result(pa_resampler *r, size_t in_length) {
> pa_assert(r);
>
> - /* Let's round up here */
> -
> - return (((((in_length + r->i_fz-1) / r->i_fz) * r->o_ss.rate) + r->i_ss.rate-1) / r->i_ss.rate) * r->o_fz;
> + /* Let's round up here to ensure that the caller will always allocate big
> + * enough output buffer. */
> + return (((((in_length + r->i_fz-1) / r->i_fz + r->leftover_buf.length / r->o_fz) * r->o_ss.rate) + r->i_ss.rate-1) / r->i_ss.rate) * r->o_fz;
A temporary variable or two here would increase readability and ease
debugging.
> }
>
> size_t pa_resampler_max_block_size(pa_resampler *r) {
> @@ -413,7 +428,7 @@ size_t pa_resampler_max_block_size(pa_resampler *r) {
>
> fs = pa_frame_size(&ss);
>
> - return (((block_size_max/fs - EXTRA_FRAMES)*r->i_ss.rate)/ss.rate)*r->i_fz;
> + return (((block_size_max / fs - EXTRA_FRAMES - r->leftover_buf.length / r->o_fz) * r->i_ss.rate) / ss.rate) * r->i_fz;
A temporary variable or two here would increase readability and ease
debugging.
> }
>
> void pa_resampler_reset(pa_resampler *r) {
> @@ -421,6 +436,11 @@ void pa_resampler_reset(pa_resampler *r) {
>
> if (r->impl_reset)
> r->impl_reset(r);
> +
> + if (r->leftover_buf.memblock) {
> + pa_memblock_unref(r->leftover_buf.memblock);
> + r->leftover_buf.length = 0;
> + }
> }
>
> pa_resample_method_t pa_resampler_get_method(pa_resampler *r) {
> @@ -1143,6 +1163,48 @@ static pa_memchunk *remap_channels(pa_resampler *r, pa_memchunk *input) {
> return&r->remap_buf;
> }
>
> +static pa_memchunk *add_leftover(pa_resampler *r, pa_memchunk *input) {
> + void *src;
> + void *dst;
> +
> + pa_assert(r);
> + pa_assert(input);
> +
> + /* Concatenate leftover and input and place the result in
> + * add_leftover_buf. */
> +
> + if (r->leftover_buf.length<= 0)
> + return input;
> +
> + r->add_leftover_buf.length = r->leftover_buf.length + input->length;
> +
> + if (!r->add_leftover_buf.memblock || r->add_leftover_buf_bytes< r->add_leftover_buf.length) {
> + if (r->add_leftover_buf.memblock)
> + pa_memblock_unref(r->add_leftover_buf.memblock);
> +
> + r->add_leftover_buf_bytes = r->add_leftover_buf.length;
> + r->add_leftover_buf.memblock = pa_memblock_new(r->mempool, r->add_leftover_buf.length);
> + }
> +
> + src = (uint8_t *) pa_memblock_acquire(r->leftover_buf.memblock);
> + dst = pa_memblock_acquire(r->add_leftover_buf.memblock);
> + memcpy(dst, src, r->leftover_buf.length);
> + pa_memblock_release(r->leftover_buf.memblock);
> +
> + if (input->length> 0) {
> + src = (uint8_t *) pa_memblock_acquire(input->memblock) + input->index;
> + dst = (uint8_t *) dst + r->leftover_buf.length;
> + memcpy(dst, src, input->length);
> + pa_memblock_release(input->memblock);
> + }
> +
> + pa_memblock_release(r->add_leftover_buf.memblock);
> +
> + r->leftover_buf.length = 0;
> +
> + return&r->add_leftover_buf;
> +}
> +
> static pa_memchunk *resample(pa_resampler *r, pa_memchunk *input) {
> unsigned in_n_frames, in_n_samples;
> unsigned out_n_frames, out_n_samples;
> @@ -1229,6 +1291,7 @@ void pa_resampler_run(pa_resampler *r, const pa_memchunk *in, pa_memchunk *out)
> buf = (pa_memchunk*) in;
> buf = convert_to_work_format(r, buf);
> buf = remap_channels(r, buf);
> + buf = add_leftover(r, buf);
> buf = resample(r, buf);
>
> if (buf->length) {
> @@ -1266,7 +1329,24 @@ static void libsamplerate_resample(pa_resampler *r, const pa_memchunk *input, un
> data.end_of_input = 0;
>
> pa_assert_se(src_process(r->src.state,&data) == 0);
> - pa_assert((unsigned) data.input_frames_used == in_n_frames);
> +
> + if (data.input_frames_used< in_n_frames) {
> + void *dst;
> +
> + r->leftover_buf.length = (in_n_frames - data.input_frames_used) * r->w_sz * r->o_ss.channels;
> +
> + if (!r->leftover_buf.memblock || r->leftover_buf_bytes< r->leftover_buf.length) {
> + if (r->leftover_buf.memblock)
> + pa_memblock_unref(r->leftover_buf.memblock);
> +
> + r->leftover_buf_bytes = r->leftover_buf.length;
> + r->leftover_buf.memblock = pa_memblock_new(r->mempool, r->leftover_buf.length);
> + }
> +
> + dst = pa_memblock_acquire(r->leftover_buf.memblock);
> + memcpy(dst, data.data_in + data.input_frames_used * r->o_ss.channels, r->leftover_buf.length);
> + pa_memblock_release(r->leftover_buf.memblock);
> + }
>
> pa_memblock_release(input->memblock);
> pa_memblock_release(output->memblock);
--
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic
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