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mpg123: rework set_format code so mpg123audiodec works with decodebin/playbin
The old code was using gst_caps_normalize() and was generally overly complex. Simplify by picking sample rate and number of channels from upstream and the sample format from the allowed caps. If the format caps is a list of strins, just pick the first one. And if the srcpad isn't linked yet, use the default format (S16). https://bugzilla.gnome.org/show_bug.cgi?id=740195
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eb89bf4030
commit
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1 changed files with 112 additions and 123 deletions
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@ -438,44 +438,12 @@ gst_mpg123_audio_dec_handle_frame (GstAudioDecoder * dec,
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static gboolean
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gst_mpg123_audio_dec_set_format (GstAudioDecoder * dec, GstCaps * input_caps)
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{
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/* Using the parsed information upstream, and the list of allowed caps
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* downstream, this code tries to find a suitable audio info. It is important
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* to keep in mind that the rate and number of channels should never deviate
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* from the one the bitstream has, otherwise mpg123 has to mix channels and/or
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* resample (and as its docs say, its internal resampler is very crude). The
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* sample format, however, can be chosen freely, because the MPEG specs do not
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* mandate any special format. Therefore, rate and number of channels are taken
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* from upstream (which parsed the MPEG frames, so the input_caps contain
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* exactly the rate and number of channels the bitstream actually has), while
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* the sample format is chosen by trying out all caps that are allowed by
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* downstream. This way, the output is adjusted to what the downstream prefers.
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*
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* Also, the new output audio info is not set immediately. Instead, it is
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* considered the "next audioinfo". The code waits for mpg123 to notice the new
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* format (= when mpg123_decode_frame() returns MPG123_AUDIO_DEC_NEW_FORMAT),
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* and then sets the next audioinfo. Otherwise, the next audioinfo is set too
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* soon, which may cause problems with mp3s containing several format headers.
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* One example would be an mp3 with the first 30 seconds using 44.1 kHz, then
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* the next 30 seconds using 32 kHz. Rare, but possible.
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*
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* STEPS:
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*
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* 1. get rate and channels from input_caps
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* 2. get allowed caps from src pad
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* 3. for each structure in allowed caps:
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* 3.1. take format
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* 3.2. if the combination of format with rate and channels is unsupported by
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* mpg123, go to (3), or exit with error if there are no more structures
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* to try
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* 3.3. create next audioinfo out of rate,channels,format, and exit
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*/
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int rate, channels;
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/* "encoding" is the sample format specifier for mpg123 */
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int encoding;
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int sample_rate, num_channels;
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GstAudioFormat format;
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GstMpg123AudioDec *mpg123_decoder;
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GstCaps *allowed_srccaps;
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guint structure_nr;
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gboolean match_found = FALSE;
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gboolean retval = FALSE;
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mpg123_decoder = GST_MPG123_AUDIO_DEC (dec);
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@ -483,7 +451,7 @@ gst_mpg123_audio_dec_set_format (GstAudioDecoder * dec, GstCaps * input_caps)
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mpg123_decoder->has_next_audioinfo = FALSE;
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/* Get rate and channels from input_caps */
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/* Get sample rate and number of channels from input_caps */
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{
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GstStructure *structure;
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gboolean err = FALSE;
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@ -492,110 +460,131 @@ gst_mpg123_audio_dec_set_format (GstAudioDecoder * dec, GstCaps * input_caps)
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* input caps structures don't make sense */
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structure = gst_caps_get_structure (input_caps, 0);
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if (!gst_structure_get_int (structure, "rate", &rate)) {
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if (!gst_structure_get_int (structure, "rate", &sample_rate)) {
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err = TRUE;
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GST_ERROR_OBJECT (dec, "Input caps do not have a rate value");
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}
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if (!gst_structure_get_int (structure, "channels", &channels)) {
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if (!gst_structure_get_int (structure, "channels", &num_channels)) {
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err = TRUE;
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GST_ERROR_OBJECT (dec, "Input caps do not have a channel value");
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}
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if (err)
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return FALSE;
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if (G_UNLIKELY (err))
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goto done;
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}
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/* Get the caps that are allowed by downstream */
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/* Get sample format from the allowed src caps */
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{
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GstCaps *allowed_srccaps_unnorm =
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GstCaps *allowed_srccaps =
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gst_pad_get_allowed_caps (GST_AUDIO_DECODER_SRC_PAD (dec));
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if (!allowed_srccaps_unnorm) {
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GST_ERROR_OBJECT (dec, "Allowed src caps are NULL");
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return FALSE;
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}
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allowed_srccaps = gst_caps_normalize (allowed_srccaps_unnorm);
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}
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/* Go through all allowed caps, pick the first one that matches */
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for (structure_nr = 0; structure_nr < gst_caps_get_size (allowed_srccaps);
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++structure_nr) {
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GstStructure *structure;
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gchar const *format_str;
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GstAudioFormat format;
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int encoding;
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if (allowed_srccaps == NULL) {
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/* srcpad is not linked (yet), so no peer information is available;
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* just use the default sample format (16 bit signed integer) */
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GST_DEBUG_OBJECT (mpg123_decoder,
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"srcpad is not linked (yet) -> using S16 sample format");
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format = GST_AUDIO_FORMAT_S16;
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encoding = MPG123_ENC_SIGNED_16;
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} else {
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gchar const *format_str;
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GValue const *format_value;
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structure = gst_caps_get_structure (allowed_srccaps, structure_nr);
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/* Look at the sample format values from the first structure */
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GstStructure *structure = gst_caps_get_structure (allowed_srccaps, 0);
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format_value = gst_structure_get_value (structure, "format");
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format_str = gst_structure_get_string (structure, "format");
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if (format_str == NULL) {
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GST_DEBUG_OBJECT (dec, "Could not get format from src caps");
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continue;
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}
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format = gst_audio_format_from_string (format_str);
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if (format == GST_AUDIO_FORMAT_UNKNOWN) {
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GST_DEBUG_OBJECT (dec, "Unknown format %s", format_str);
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continue;
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}
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switch (format) {
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case GST_AUDIO_FORMAT_S16:
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encoding = MPG123_ENC_SIGNED_16;
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break;
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case GST_AUDIO_FORMAT_S24:
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encoding = MPG123_ENC_SIGNED_24;
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break;
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case GST_AUDIO_FORMAT_S32:
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encoding = MPG123_ENC_SIGNED_32;
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break;
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case GST_AUDIO_FORMAT_U16:
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encoding = MPG123_ENC_UNSIGNED_16;
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break;
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case GST_AUDIO_FORMAT_U24:
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encoding = MPG123_ENC_UNSIGNED_24;
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break;
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case GST_AUDIO_FORMAT_U32:
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encoding = MPG123_ENC_UNSIGNED_32;
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break;
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case GST_AUDIO_FORMAT_F32:
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encoding = MPG123_ENC_FLOAT_32;
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break;
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default:
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GST_DEBUG_OBJECT (dec,
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"Format %s in srccaps is not supported", format_str);
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continue;
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}
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{
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int err;
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/* Cleanup old formats & set new one */
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mpg123_format_none (mpg123_decoder->handle);
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err = mpg123_format (mpg123_decoder->handle, rate, channels, encoding);
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if (err != MPG123_OK) {
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GST_DEBUG_OBJECT (dec,
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"mpg123 cannot use caps %" GST_PTR_FORMAT
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" because mpg123_format() failed: %s", structure,
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mpg123_strerror (mpg123_decoder->handle));
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continue;
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if (GST_VALUE_HOLDS_LIST (format_value)) {
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/* if value is a format list, pick the first entry */
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GValue const *fmt_list_value =
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gst_value_list_get_value (format_value, 0);
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format_str = g_value_get_string (fmt_list_value);
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} else if (G_VALUE_HOLDS_STRING (format_value)) {
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/* if value is a string, use it directly */
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format_str = g_value_get_string (format_value);
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} else {
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GST_ERROR_OBJECT (mpg123_decoder,
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"format value in caps structure %" GST_PTR_FORMAT
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" is of invalid type (must be plain string or string list)",
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structure);
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format_str = NULL;
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}
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format = GST_AUDIO_FORMAT_UNKNOWN;
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/* get the format value from the string */
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if (G_LIKELY (format_str != NULL)) {
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format = gst_audio_format_from_string (format_str);
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if (G_UNLIKELY (format == GST_AUDIO_FORMAT_UNKNOWN)) {
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GST_ERROR_OBJECT (mpg123_decoder, "format \"%s\" is invalid",
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format_str);
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}
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}
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/* convert format to mpg123 encoding */
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if (G_LIKELY (format != GST_AUDIO_FORMAT_UNKNOWN)) {
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switch (format) {
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case GST_AUDIO_FORMAT_S16:
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encoding = MPG123_ENC_SIGNED_16;
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break;
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case GST_AUDIO_FORMAT_S24:
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encoding = MPG123_ENC_SIGNED_24;
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break;
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case GST_AUDIO_FORMAT_S32:
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encoding = MPG123_ENC_SIGNED_32;
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break;
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case GST_AUDIO_FORMAT_U16:
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encoding = MPG123_ENC_UNSIGNED_16;
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break;
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case GST_AUDIO_FORMAT_U24:
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encoding = MPG123_ENC_UNSIGNED_24;
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break;
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case GST_AUDIO_FORMAT_U32:
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encoding = MPG123_ENC_UNSIGNED_32;
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break;
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case GST_AUDIO_FORMAT_F32:
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encoding = MPG123_ENC_FLOAT_32;
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break;
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default:
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GST_DEBUG_OBJECT (dec,
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"Format %s in srccaps is not supported", format_str);
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goto done;
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}
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}
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gst_caps_unref (allowed_srccaps);
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}
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gst_audio_info_init (&(mpg123_decoder->next_audioinfo));
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gst_audio_info_set_format (&(mpg123_decoder->next_audioinfo), format, rate,
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channels, NULL);
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GST_LOG_OBJECT (dec, "The next audio format is: %s, %u Hz, %u channels",
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format_str, rate, channels);
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mpg123_decoder->has_next_audioinfo = TRUE;
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match_found = TRUE;
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break;
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}
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gst_caps_unref (allowed_srccaps);
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/* Sample rate, number of channels, and sample format are known at this point.
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* Set the audioinfo structure's values and the mpg123 format. */
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{
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int err;
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return match_found;
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/* clear all existing format settings from the mpg123 instance */
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mpg123_format_none (mpg123_decoder->handle);
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/* set the chosen format */
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err =
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mpg123_format (mpg123_decoder->handle, sample_rate, num_channels,
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encoding);
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if (err != MPG123_OK) {
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GST_WARNING_OBJECT (dec,
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"mpg123_format() failed: %s",
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mpg123_strerror (mpg123_decoder->handle));
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} else {
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gst_audio_info_init (&(mpg123_decoder->next_audioinfo));
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gst_audio_info_set_format (&(mpg123_decoder->next_audioinfo), format,
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sample_rate, num_channels, NULL);
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GST_LOG_OBJECT (dec, "The next audio format is: %s, %u Hz, %u channels",
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gst_audio_format_to_string (format), sample_rate, num_channels);
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mpg123_decoder->has_next_audioinfo = TRUE;
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retval = TRUE;
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}
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}
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done:
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return retval;
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}
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